All Problems
Output a string to the console
Write the string
"Hello World!" to STDOUT
php
echo 'Hello World!';
/****
* For some (security)reason I couldn't
* submit this without adding a space to
* the functionname. Please remove it :)
****/
// The correct way in command line-mode. :)
f write(STDOUT, "Hello World!\n");
* For some (security)reason I couldn't
* submit this without adding a space to
* the functionname. Please remove it :)
****/
// The correct way in command line-mode. :)
f write(STDOUT, "Hello World!\n");
clojure
(println "Hello World!")
fantom
echo("Hello World!")
Retrieve a string containing ampersands from the variables in a url
My PHP script first does a query to obtain customer info for a form. The form has first name and last name fields among others. The customer has put entries such as
The script variable for first name $_REQUEST
I have tried various functions like urldecode but all to no avail. I even tried encoding the url before the view screen is painted so that the url looks like
Of course this fails for the same reasons. What is a better approach?
"Ron & Jean" in the first name field in the database. Then the edit form script is called with variables such as
"http://myserver.com/custinfo/edit.php?mode=view&fname=Ron & Jean&lname=Smith".
The script variable for first name $_REQUEST
['firstname'] never gets beyond the "Ron" value because of the ampersand in the data.
I have tried various functions like urldecode but all to no avail. I even tried encoding the url before the view screen is painted so that the url looks like
"http://myserver/custinfo/edit.php?mode=view&fname="Ronxxnbsp;xxamp;xxnbsp;Jean"&lname=SMITH". (sorry I had to add the xx to replace the ampersand or it didn't display meaningful url contents the browser sees.)
Of course this fails for the same reasons. What is a better approach?
php
echo("The given input URL is mal-formed; it should be URL-encoded. Use urldecode() on each argument to decode it.");
$url = parse_url("http://myserver.com/custinfo/edit.php?mode=view&fname=Ron & Jean&lname=Smith");
$query = $url['query'];
$query = preg_replace("/&(?=[^=]*&)/", "%26", $query);
parse_str($query, $querystring);
var_dump($querystring);
the result is >> array(3) {
["mode"]=>
string(4) "view"
["fname"]=>
string(10) "Ron & Jean"
["lname"]=>
string(5) "Smith"
}
/************************
* This is definitely not what this site is about
* This is not a site where you can get help with various problems
* It's a site where you can say:
* "How do you do the following in your language"
*
*************
*
* Anyway...
* I would use urlencode like you have tried
* (or to be on the safe side: rawurlencode() )
************************/
$parameter = "Bart & Lisa";
echo "<a href='".basename(__FILE__)."?fname=".$parameter."'>?fname=".$parameter."</a><br />\n";
echo "<a href='".basename(__FILE__)."?fname=".rawurlencode($parameter)."'>?fname=".rawurlencode($parameter)."</a><br />\n";
echo "<pre>", print_r($_REQUEST, true), "</pre>";
/***************
* Try to save this as a file and run the script
************
* If you hover the mouse over the link, they will look exactly the same
* but if you click them, they will output differently
***************/
// Cheers, "Josso"
* This is definitely not what this site is about
* This is not a site where you can get help with various problems
* It's a site where you can say:
* "How do you do the following in your language"
*
*************
*
* Anyway...
* I would use urlencode like you have tried
* (or to be on the safe side: rawurlencode() )
************************/
$parameter = "Bart & Lisa";
echo "<a href='".basename(__FILE__)."?fname=".$parameter."'>?fname=".$parameter."</a><br />\n";
echo "<a href='".basename(__FILE__)."?fname=".rawurlencode($parameter)."'>?fname=".rawurlencode($parameter)."</a><br />\n";
echo "<pre>", print_r($_REQUEST, true), "</pre>";
/***************
* Try to save this as a file and run the script
************
* If you hover the mouse over the link, they will look exactly the same
* but if you click them, they will output differently
***************/
// Cheers, "Josso"
echo("The given input URL is mal-formed; it should be URL-encoded. Use urldecode() on each argument to decode it.");
$url = parse_url("http://myserver.com/custinfo/edit.php?mode=view&fname=Ron & Jean&lname=Smith");
$query = $url['query'];
$query = preg_replace("/&(?=[^=]*&)/", "%26", $query);
parse_str($query, $querystring);
var_dump($querystring);
the result is >> array(3) {
["mode"]=>
string(4) "view"
["fname"]=>
string(10) "Ron & Jean"
["lname"]=>
string(5) "Smith"
}
clojure
(->> {"mode" "view"
"fname" "Ron & Jean"
"lname" "Smith"}
(map #(str (URLEncoder/encode (first %) "UTF-8")
"="
(URLEncoder/encode (second %) "UTF-8")))
(reduce (fn [url e] (str url "&" e))
"http://myserver.com/custinfo/edit.php"))
"fname" "Ron & Jean"
"lname" "Smith"}
(map #(str (URLEncoder/encode (first %) "UTF-8")
"="
(URLEncoder/encode (second %) "UTF-8")))
(reduce (fn [url e] (str url "&" e))
"http://myserver.com/custinfo/edit.php"))
fantom
encoded := `http://myserver.com/custinfo/edit.php`.plusQuery(
["fname":"Ron & Jean", "lname":"Smith"]).encode
echo(encoded)
["fname":"Ron & Jean", "lname":"Smith"]).encode
echo(encoded)
string-wrap
Wrap the string
Expected output:
> The quick brown fox jumps over the lazy dog. The quick brown fox jumps over t
> he lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox
> jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The qui
> ck brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy
> dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps o
> ver the lazy dog. The quick brown fox jumps over the lazy dog.
"The quick brown fox jumps over the lazy dog. " repeated ten times to a max width of 78 chars, starting each line with "> "
Expected output:
> The quick brown fox jumps over the lazy dog. The quick brown fox jumps over t
> he lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox
> jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The qui
> ck brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy
> dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps o
> ver the lazy dog. The quick brown fox jumps over the lazy dog.
php
foreach(str_split(str_repeat("The quick brown fox jumps over the lazy dog. ", 10), 77) as $line)
printf("> %s\n", trim($line));
printf("> %s\n", trim($line));
clojure
(defn string-wrap [s]
(if (= 0 (count s))
nil
(lazy-seq (cons (apply str (take 78 s))
(string-wrap (drop 78 s))))))
(let [s (apply str (repeat 10 "The quick brown fox jumps over the lazy dog. "))]
(doseq [line (string-wrap s)]
(println "> " line)))
(if (= 0 (count s))
nil
(lazy-seq (cons (apply str (take 78 s))
(string-wrap (drop 78 s))))))
(let [s (apply str (repeat 10 "The quick brown fox jumps over the lazy dog. "))]
(doseq [line (string-wrap s)]
(println "> " line)))
fantom
s:=Str[,].fill("The quick brown fox jumps over the lazy dog. ",10).join
while(s.size>0){
echo("> "+s[0..(77.min(s.size))-1])
s=(s.size>77)?s[77..-1].trim : ""
}
while(s.size>0){
echo("> "+s[0..(77.min(s.size))-1])
s=(s.size>77)?s[77..-1].trim : ""
}
Define a string containing special characters
Define the literal string
"\#{'}${"}/"
php
$special = "\\#{'}\${\"}/";
$special = '\#{\'}${"}/';
clojure
(def special "\\#{'}${\"}/")
fantom
special := Str<|\#{'}${"}/|>
Define a multiline string
Define the string:
"This
Is
A
Multiline
String"
php
$multiline = <<<ML
This
Is
A
Multiline
String
ML;
This
Is
A
Multiline
String
ML;
$multiline = "This
Is
A
Multiline
String";
Is
A
Multiline
String";
$multiline = "This\nIs\nA\nMultiline\nString";
clojure
(def multiline "This\nIs\nA\nMultiline\nString")
fantom
s := "This
Is
A
Multiline
String"
Is
A
Multiline
String"
Define a string containing variables and expressions
Given variables a=3 and b=4 output
"3+4=7"
php
echo "$a+$b=".($a+$b);
printf("%d+%d=%d\n", $a, $b, $a + $b);
clojure
(format "%d + %d = %d" a b (+ a b))
fantom
echo("$a+$b=${a+b}")
Reverse the characters in a string
Given the string
"reverse me", produce the string "em esrever"
php
$reversed = strrev("reverse me");
clojure
(require '[clojure.contrib.str-utils2 :as str])
(str/reverse "reverse me")
(str/reverse "reverse me")
(apply str (reverse "reverse me"))
fantom
"reverse me".reverse
Reverse the words in a string
Given the string
"This is a end, my only friend!", produce the string "friend! only my end, the is This"
php
$reversed_words = implode(" ", array_reverse(explode(" ", "This is the end, my only friend!")));
clojure
(require '[clojure.contrib.str-utils2 :as str])
(str/join " " (reverse (str/split "this is the end, my only friend!" #" ")))
(str/join " " (reverse (str/split "this is the end, my only friend!" #" ")))
(apply str (interpose " " (reverse (re-seq #"[^\s]+" "This is the end, my only friend!"))))
fantom
"This is a end, my only friend!".split.reverse.join(" ")
Text wrapping
Wrap the string
> The quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog.
"The quick brown fox jumps over the lazy dog. " repeated ten times to a max width of 78 chars, starting each line with "> ", yielding this result:
> The quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog.
php
$s = str_repeat("The quick brown fox jumps over the lazy dog. ", 10);
$s = wordwrap($s, 76, "WRAP");
$s = explode("WRAP", $s);
foreach ($s as $part) {
$res .= "> " . $part . "\n";
}
echo $res;
$s = wordwrap($s, 76, "WRAP");
$s = explode("WRAP", $s);
foreach ($s as $part) {
$res .= "> " . $part . "\n";
}
echo $res;
echo '> '.wordwrap(str_repeat('The quick brown fox jumps over the lazy dog. ', 10), 70,"\n> ")."\n";
clojure
(doseq [line (re-seq #".{0,70} "
(apply str
(repeat 10 "The quick brown fox jumps over the lazy dog. ")))]
(println ">" line))
(apply str
(repeat 10 "The quick brown fox jumps over the lazy dog. ")))]
(println ">" line))
fantom
buf := Buf()
10.times { buf.writeChars("The quick brown fox jumps over the lazy dog. ") }
buf.flip
out := Env.cur.out
sep := ">"; max := 72 - sep.size - 1
acc := 0; Str? s := null
while ((s = buf.readStrToken) != null)
{
if (acc == 0)
out.print(sep)
acc += s.size
if (acc > max)
{
out.print("\n$sep")
acc = s.size
}
out.print(" $s")
buf.readStrToken(4096) { !it.isSpace }
acc++
}
10.times { buf.writeChars("The quick brown fox jumps over the lazy dog. ") }
buf.flip
out := Env.cur.out
sep := ">"; max := 72 - sep.size - 1
acc := 0; Str? s := null
while ((s = buf.readStrToken) != null)
{
if (acc == 0)
out.print(sep)
acc += s.size
if (acc > max)
{
out.print("\n$sep")
acc = s.size
}
out.print(" $s")
buf.readStrToken(4096) { !it.isSpace }
acc++
}
Remove leading and trailing whitespace from a string
Given the string
" hello " return the string "hello".
php
$hello_trimmed = trim(" hello ");
clojure
(use 'clojure.contrib.str-utils2)
(trim " hello ")
(trim " hello ")
(clojure.string/trim " hello ")
(.trim " hello ")
fantom
s := " hello ".trim
Simple substitution cipher
Take a string and return the ROT13 and ROT47 (Check Wikipedia) version of the string.
For example:
String is: Hello World #123
ROT13 returns: Uryyb Jbeyq #123
ROT47 returns: w6==@ (@C=5 R`ab
For example:
String is: Hello World #123
ROT13 returns: Uryyb Jbeyq #123
ROT47 returns: w6==@ (@C=5 R`ab
php
function rot13($str) {
return strtr($str,
"NOPQRSTUVWXYZnopqrstuvwxyzABCDEFGHIJKLMabcdefghijklm",
"ABCDEFGHIJKLMabcdefghijklmNOPQRSTUVWXYZnopqrstuvwxyz");
}
function str_rot47($str) {
return strtr($str,
'!"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~',
'PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~!"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO');
}
echo str_rot13("Hello World #123"); // builtin version
echo str_rot47("Hello World #123"); // homemade version
echo rot13("Hello World #123"); // homemade version
return strtr($str,
"NOPQRSTUVWXYZnopqrstuvwxyzABCDEFGHIJKLMabcdefghijklm",
"ABCDEFGHIJKLMabcdefghijklmNOPQRSTUVWXYZnopqrstuvwxyz");
}
function str_rot47($str) {
return strtr($str,
'!"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~',
'PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~!"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO');
}
echo str_rot13("Hello World #123"); // builtin version
echo str_rot47("Hello World #123"); // homemade version
echo rot13("Hello World #123"); // homemade version
clojure
(use 'clojure.contrib.cond)
(defn rot13 [s]
(reduce str
(map #(char (let [c (bit-and (int (char %)) 0xDF)]
(+ % (cond-let [i]
(and (>= c (int \A)) (<= c (int \M))) 13
(and (>= c (int \N)) (<= c (int \Z))) -13
true 0))))
(map #(int (char %)) s))))
(defn rot47 [s]
(reduce str
(map #(char (+ % (cond-let [i]
(and (>= % (int \!)) (<= % (int \O))) 47
(and (>= % (int \P)) (<= % (int \~))) -47
true 0)))
(map #(int (char %)) s))))
(defn rot13 [s]
(reduce str
(map #(char (let [c (bit-and (int (char %)) 0xDF)]
(+ % (cond-let [i]
(and (>= c (int \A)) (<= c (int \M))) 13
(and (>= c (int \N)) (<= c (int \Z))) -13
true 0))))
(map #(int (char %)) s))))
(defn rot47 [s]
(reduce str
(map #(char (+ % (cond-let [i]
(and (>= % (int \!)) (<= % (int \O))) 47
(and (>= % (int \P)) (<= % (int \~))) -47
true 0)))
(map #(int (char %)) s))))
fantom
rot := |Str s, |Int c -> Int| remap -> Str|
{
rs := ""
s.each { rs += remap(it).toChar }
return rs
}
rot13 := |Str s -> Str|
{
rot(s) |Int c -> Int|
{
lc := c.lower
c += (lc >= 'a' && lc <= 'm') ? 13
: ((lc >= 'n' && lc <= 'z') ? -13 : 0)
return c
}
}
rot47 := |Str s -> Str|
{
rot(s) |Int c -> Int|
{
c += (c >= '!' && c <= 'O') ? 47
: ((c >= 'P' && c <= '~') ? -47 : 0)
return c
}
}
s := "Hello World #123"
echo("s=$s")
echo("rot13=${rot13(s)}")
echo("rot47=${rot47(s)}")
{
rs := ""
s.each { rs += remap(it).toChar }
return rs
}
rot13 := |Str s -> Str|
{
rot(s) |Int c -> Int|
{
lc := c.lower
c += (lc >= 'a' && lc <= 'm') ? 13
: ((lc >= 'n' && lc <= 'z') ? -13 : 0)
return c
}
}
rot47 := |Str s -> Str|
{
rot(s) |Int c -> Int|
{
c += (c >= '!' && c <= 'O') ? 47
: ((c >= 'P' && c <= '~') ? -47 : 0)
return c
}
}
s := "Hello World #123"
echo("s=$s")
echo("rot13=${rot13(s)}")
echo("rot47=${rot47(s)}")
Make a string uppercase
Transform
"Space Monkey" into "SPACE MONKEY"
php
echo strtoupper("Space Monkey");
clojure
(.toUpperCase "Space Monkey")
fantom
s := "Space Monkey".localeUpper
Make a string lowercase
Transform
"Caps ARE overRated" into "caps are overrated"
php
echo strtolower("Caps ARE overRated");
clojure
(.toLowerCase "Caps ARE overRated")
fantom
s := "Caps ARE overRated".localeLower
Capitalise the first letter of each word
Transform
"man OF stEEL" into "Man Of Steel"
php
echo ucwords(strtolower("man OF stEEL"));
clojure
(use 'clojure.contrib.str-utils2)
(join " " (map capitalize (split "man OF stEEL" #" ")))
(join " " (map capitalize (split "man OF stEEL" #" ")))
fantom
"man OF stEEL".split.map { it.localeLower.localeCapitalize }.join(" ")
Find the distance between two points
php
$distance = sqrt( pow(($x2 - $x1), 2) + pow(($y2 - $y1),2) );
class Point2D {
var $x;
var $y;
function __construct($x, $y) {
$this->x = $x;
$this->y = $y;
}
}
$a = new Point2D($x1,$y1);
$b = new Point2D($x2,$y2);
$distance = sqrt( pow(($b->x - $a->x), 2) + pow(($b->y - $a->y),2) );
var $x;
var $y;
function __construct($x, $y) {
$this->x = $x;
$this->y = $y;
}
}
$a = new Point2D($x1,$y1);
$b = new Point2D($x2,$y2);
$distance = sqrt( pow(($b->x - $a->x), 2) + pow(($b->y - $a->y),2) );
clojure
(defstruct point :x :y)
(defn distance
"Euclidean distance between 2 points"
[p1 p2]
(Math/pow (+ (Math/pow (- (:x p1) (:x p2)) 2)
(Math/pow (- (:y p1) (:y p2)) 2))
0.5))
(distance (struct point 0 0) (struct point 1 1)) ; => 1.4142135623730951
(defn distance
"Euclidean distance between 2 points"
[p1 p2]
(Math/pow (+ (Math/pow (- (:x p1) (:x p2)) 2)
(Math/pow (- (:y p1) (:y p2)) 2))
0.5))
(distance (struct point 0 0) (struct point 1 1)) ; => 1.4142135623730951
(defn distance
"Euclidean distance between 2 points"
[[x1 y1] [x2 y2]]
(Math/sqrt
(+ (Math/pow (- x1 x2) 2)
(Math/pow (- y1 y2) 2))))
(distance [2 2] [3 3])
"Euclidean distance between 2 points"
[[x1 y1] [x2 y2]]
(Math/sqrt
(+ (Math/pow (- x1 x2) 2)
(Math/pow (- y1 y2) 2))))
(distance [2 2] [3 3])
fantom
px1 := 34.0f; py1 := 78.0f; px2 := 67.0f; py2 := -45.0f
distance := |Float x1, Float y1, Float x2, Float y2 -> Float|
{ ((x2-x1).pow(2.0f) + (y2-y1).pow(2.0f)).sqrt }
distance(px1, py1, px2, py2)
distance := |Float x1, Float y1, Float x2, Float y2 -> Float|
{ ((x2-x1).pow(2.0f) + (y2-y1).pow(2.0f)).sqrt }
distance(px1, py1, px2, py2)
Zero pad a number
Given the number 42, pad it to 8 characters like 00000042
php
echo str_pad(42, 8, 0, STR_PAD_LEFT);
printf("%08d", 42);
clojure
(defn pad
([x] (if (> 8 (.length (str x))) (pad (str 0 x)) (str x)))
)
([x] (if (> 8 (.length (str x))) (pad (str 0 x)) (str x)))
)
(defn pad [x]
(format "%08d" x))
(format "%08d" x))
(format "%08d" 42)
fantom
formatted := 42.toStr.padl(8, '0')
formatted := 42.toLocale("00000000")
Right Space pad a number
Given the number 1024 right pad it to 6 characters
"1024 "
php
echo str_pad(1024, 6, " ");
printf("%s ", 1024);
clojure
(let [s (str 1024)
l (count s)]
(str s (reduce str (repeat (- 6 l) " "))))
l (count s)]
(str s (reduce str (repeat (- 6 l) " "))))
fantom
formatted := 1024.toStr.padr(6)
Format a decimal number
Format the number 7/8 as a decimal with 2 places: 0.88
php
printf("%.2g", 7/8);
echo round(7/8, 2);
clojure
(format "%3.2f" (/ 7.0 8))
(* 0.01 (Math/round (* 100 (float (/ 7 8)))))
fantom
formatted := (7.0/8.0).toLocale("0.00")
Left Space pad a number
Given the number 73 left pad it to 10 characters
" 73"
php
echo str_pad(73, 10, " ", STR_PAD_LEFT);
printf("%10d", 73);
clojure
(let [s (str 73)
l (count s)]
(str (reduce str (repeat (- 10 l) " ")) s ))
l (count s)]
(str (reduce str (repeat (- 10 l) " ")) s ))
fantom
formatted := 73.toStr.padl(10)
Generate a random integer in a given range
Produce a random integer between 100 and 200 inclusive
php
$r = mt_rand(100, 200);
clojure
(+ (rand-int (- 201 100)) 100)
fantom
r := Int.random(100..200)
Generate a repeatable random number sequence
Initialise a random number generator with a seed and generate five decimal values. Reset the seed and produce the same values.
php
mt_srand(9876);
$r1 = array();
foreach(range(1,5) as $i) {
$r1[$i] = mt_rand(1,100);
}
mt_srand(9876);
$r2 = array();
foreach(range(1,5) as $i) {
$r2[$i] = mt_rand(1,100);
}
$r1 = array();
foreach(range(1,5) as $i) {
$r1[$i] = mt_rand(1,100);
}
mt_srand(9876);
$r2 = array();
foreach(range(1,5) as $i) {
$r2[$i] = mt_rand(1,100);
}
clojure
(dotimes [_ 2]
(let [r (java.util.Random. 12345)]
(dotimes [_ 5]
(println (.nextInt r 100))))
(println))
(let [r (java.util.Random. 12345)]
(dotimes [_ 5]
(println (.nextInt r 100))))
(println))
fantom
rand := Random.makeSeeded(12345)
first := Int[,].fill(0,5).map { rand.next(100..200) }
rand2 := Random.makeSeeded(12345)
second := Int[,].fill(0,5).map { rand2.next(100..200) }
first := Int[,].fill(0,5).map { rand.next(100..200) }
rand2 := Random.makeSeeded(12345)
second := Int[,].fill(0,5).map { rand2.next(100..200) }
Check if a string matches a regular expression
Display
"ok" if "Hello" matches /[A-Z][a-z]+/
php
if(ereg('[A-Za-z]+', 'Hello')) {
echo "ok";
}
echo "ok";
}
if(preg_match('/[A-Za-z]+/', 'Hello')>0) {
echo "ok";
}
echo "ok";
}
clojure
(if (re-matches #"[A-Z][a-z]+" "Hello")
(println "ok"))
(println "ok"))
fantom
if (Regex<|[A-Z][a-z]+|>.matches("Hello"))
echo("ok")
echo("ok")
Check if a string matches with groups
Display
"two" if "one two three" matches /one (.*) three/
php
preg_match('/one (.*) three/', 'one two three', $matches);
echo $matches[1];
echo $matches[1];
ereg('one (.*) three', 'one two three', $regs);
echo $regs[1];
echo $regs[1];
clojure
(if-let [groups (re-matches #"one (.*) three" "one two three")]
(println (second groups)))
(println (second groups)))
fantom
m := Regex<|one (.*) three|>.matcher("one two three")
if (m.matches)
echo("${m.group(1)}")
if (m.matches)
echo("${m.group(1)}")
Check if a string contains a match to a regular expression
Display
"ok" if "abc 123 @#$" matches /\d+/
php
if (preg_match("/\d+/", "abc 123 @#$"))
echo "ok";
echo "ok";
clojure
(if (re-find #"\d+" "abc 123 @#$")
(println "ok"))
(println "ok"))
fantom
m := Regex<|\d+|>.matcher("abc 123 @#\$")
if (m.find)
echo("ok")
if (m.find)
echo("ok")
Loop through a string matching a regex and performing an action for each match
Create a list
[fish1,cow3,boat4] when matching "(fish):1 sausage (cow):3 tree (boat):4" with regex /\((\w+)\):(\d+)/
php
preg_match_all("/\((\w+)\):(\d+)/", "(fish):1 sausage (cow):3 tree (boat):4", $matches);
for ($i=0, $c=count($matches[0]); $i < $c; $i++) {
$list[] = $matches[1][$i].$matches[2][$i];
}
for ($i=0, $c=count($matches[0]); $i < $c; $i++) {
$list[] = $matches[1][$i].$matches[2][$i];
}
clojure
(let [matcher (re-matcher #"\((\w+)\):(\d+)" "(fish):1 sausage (cow):3 tree (boat):4")]
(loop [match (re-find matcher)
lst []]
(if match
(recur (re-find matcher) (conj lst (str (second match) (nth match 2))))
lst)))
(loop [match (re-find matcher)
lst []]
(if match
(recur (re-find matcher) (conj lst (str (second match) (nth match 2))))
lst)))
fantom
m := Regex<|\((\w+)\):(\d+)|>.matcher(s)
list := Str[,]
while (m.find) { list.add("${m.group(1)}${m.group(2)}") }
list := Str[,]
while (m.find) { list.add("${m.group(1)}${m.group(2)}") }
Replace the first regex match in a string with a static string
Transform
"Red Green Blue" into "R*d Green Blue" by replacing /e/ with "*"
php
echo preg_replace('/e/', '*', "Red Green Blue", 1);
clojure
(.replaceFirst (re-matcher #"e" "Red Green Blue") "*")
fantom
replaced := Regex<|e|>.split("Red Green Blue",2).join("*")
Replace all regex matches in a string with a static string
Transform
"She sells sea shells" into "She X X shells" by replacing /se\w+/ with "X"
php
echo preg_replace('/se\w+/', 'X', 'She sells sea shells');
clojure
(.replaceAll (re-matcher #"se\w+" "She sells sea shells") "X")
fantom
replaced := Regex<|se\w+|>.split("She sells sea shells").join("X")
Replace all regex matches in a string with a dynamic string
Transform
"The {Quick} Brown {Fox}" into "The kciuQ Brown xoF" by reversing words in braces using the regex /\{(\w+)\}/.
php
// We have to use the e-modifier
preg_replace("/\{(\w+)\}/e", "''.strrev('\\1').''", "The {Quick} Brown {Fox}");
preg_replace("/\{(\w+)\}/e", "''.strrev('\\1').''", "The {Quick} Brown {Fox}");
clojure
(def *string* "The {Quick} Brown {Fox}")
(def *regex* (re-pattern #"\{(\w+)\}"))
(println
(loop [result ""
src *string*
replace-strs (re-seq *regex* *string*)]
(if (empty? src)
result
(let [[match replacement] (first replace-strs)]
(if (= (first src) (first match))
; At the beginning of a sequence that should be replaced.
; Do replacement of a single match
(recur (str result (apply str (reverse replacement)))
(drop (count match) src)
(rest replace-strs))
; else, just copy one char from the source to the result
(recur (str result (first src))
(rest src)
replace-strs))))))
(def *regex* (re-pattern #"\{(\w+)\}"))
(println
(loop [result ""
src *string*
replace-strs (re-seq *regex* *string*)]
(if (empty? src)
result
(let [[match replacement] (first replace-strs)]
(if (= (first src) (first match))
; At the beginning of a sequence that should be replaced.
; Do replacement of a single match
(recur (str result (apply str (reverse replacement)))
(drop (count match) src)
(rest replace-strs))
; else, just copy one char from the source to the result
(recur (str result (first src))
(rest src)
replace-strs))))))
(clojure.string/replace "The {Quick} Brown {Fox}"
#"\{(\w+)\}"
(fn [[_ word]] (apply str (reverse word))))
#"\{(\w+)\}"
(fn [[_ word]] (apply str (reverse word))))
fantom
s := "The {Quick} Brown {Fox}"
m := Regex<|\{(\w+)\}|>.matcher(s)
buf := StrBuf(s.size)
last := 0
while (m.find)
{
buf.add(s[last..m.start-1]).add(m.group(1).reverse)
last = m.end
}
buf.add(s[last..-1])
replaced := buf.toStr
m := Regex<|\{(\w+)\}|>.matcher(s)
buf := StrBuf(s.size)
last := 0
while (m.find)
{
buf.add(s[last..m.start-1]).add(m.group(1).reverse)
last = m.end
}
buf.add(s[last..-1])
replaced := buf.toStr
Define an empty list
Assign the variable
"list" to a list with no elements
php
$list = array();
clojure
(list)
'()
fantom
list := [,]
Define a static list
Define the list
[One, Two, Three, Four, Five]
php
$list = array("One", "Two", "Three", "Four", "Five");
$list = array();
$list[] = "One";
$list[] = "Two";
$list[] = "Three";
$list[] = "Four";
$list[] = "Five";
$list[] = "One";
$list[] = "Two";
$list[] = "Three";
$list[] = "Four";
$list[] = "Five";
<?php
$list = new SplFixedArray(5);
$list[0] = "One";
$list[1] = "Two";
$list[2] = "Three";
$list[3] = "Four";
$list[4] = "Five";
?>
$list = new SplFixedArray(5);
$list[0] = "One";
$list[1] = "Two";
$list[2] = "Three";
$list[3] = "Four";
$list[4] = "Five";
?>
clojure
(def a '[One Two Three Four Five])
fantom
list := ["One", "Two", "Three", "Four", "Five"]
Join the elements of a list, separated by commas
Given the list
[Apple, Banana, Carrot] produce "Apple, Banana, Carrot"
php
$string = implode(", ", $fruits);
clojure
(apply str (interpose ", " '("Apple" "Banana" "Carrot")))
fantom
["Apple", "Banana", "Carrot"].join(", ")
Join the elements of a list, in correct english
Create a function join that takes a List and produces a string containing an english language concatenation of the list. It should work with the following examples:
join(
join(
join(
join(
join(
[Apple, Banana, Carrot]) = "Apple, Banana, and Carrot"
join(
[One, Two]) = "One and Two"
join(
[Lonely]) = "Lonely"
join(
[]) = ""
php
function ImplodeToEnglish($array) {
// sanity check
if (!$array || !count ($array))
return "";
// get last element
$last = array_pop($array);
// if it was the only element - return it
if (!count ($array))
return $last;
return implode(", ", $array)." and ".$last;
}
//example
ImplodeToEnglish(array("Apple", "Banana")); // returns: Apple and Banana
// sanity check
if (!$array || !count ($array))
return "";
// get last element
$last = array_pop($array);
// if it was the only element - return it
if (!count ($array))
return $last;
return implode(", ", $array)." and ".$last;
}
//example
ImplodeToEnglish(array("Apple", "Banana")); // returns: Apple and Banana
clojure
(defn join [lst]
(cond
(= (count lst) 0) ""
(= (count lst) 1) (first lst)
(= (count lst) 2) (str (first lst) " and " (second lst))
(> (count lst) 2) (loop [lst lst sb (StringBuilder.)]
(if (empty? lst)
(.toString sb)
(recur (rest lst) (.append sb (cond
(> (count lst) 2) (str (first lst) ", ")
(> (count lst) 1) (str (first lst) ", and ")
(= (count lst) 1) (str (first lst)))))))))
(cond
(= (count lst) 0) ""
(= (count lst) 1) (first lst)
(= (count lst) 2) (str (first lst) " and " (second lst))
(> (count lst) 2) (loop [lst lst sb (StringBuilder.)]
(if (empty? lst)
(.toString sb)
(recur (rest lst) (.append sb (cond
(> (count lst) 2) (str (first lst) ", ")
(> (count lst) 1) (str (first lst) ", and ")
(= (count lst) 1) (str (first lst)))))))))
(defn join
([lst]
(join lst false))
([lst is-long]
(condp = (count lst)
0 ""
1 (first lst)
2 (str (first lst) (if is-long ",") " and " (second lst))
(str (first lst) ", " (join (rest lst) true)))))
([lst]
(join lst false))
([lst is-long]
(condp = (count lst)
0 ""
1 (first lst)
2 (str (first lst) (if is-long ",") " and " (second lst))
(str (first lst) ", " (join (rest lst) true)))))
fantom
join := |List list -> Str|
{
switch(list.size)
{
case 0: return ""
case 1: return list[0]
case 2: return list.join(" and ")
default: return list[0..-2].join(", ") + ", and " + list[-1]
}
}
echo(join(["Apple", "Banana", "Carrot"]))
echo(join(["One", "Two"]))
echo(join(["Lonely"]))
echo(join([,]))
{
switch(list.size)
{
case 0: return ""
case 1: return list[0]
case 2: return list.join(" and ")
default: return list[0..-2].join(", ") + ", and " + list[-1]
}
}
echo(join(["Apple", "Banana", "Carrot"]))
echo(join(["One", "Two"]))
echo(join(["Lonely"]))
echo(join([,]))
Produce the combinations from two lists
Given two lists, produce the list of tuples formed by taking the combinations from the individual lists. E.g. given the letters
["a", "b", "c"] and the numbers [4, 5], produce the list: [["a", 4], ["b", 4], ["c", 4], ["a", 5], ["b", 5], ["c", 5]]
php
foreach ($short as $s) {
foreach ($long as $l) {
$list[] = array($l, $s);
}
}
foreach ($long as $l) {
$list[] = array($l, $s);
}
}
clojure
(defn combine [lst1 lst2]
(mapcat (fn [x] (map #(list % x) lst1)) lst2))
(mapcat (fn [x] (map #(list % x) lst1)) lst2))
(mapcat (fn [x] (map #(list % x) ["a", "b", "c"])) [4, 5])
fantom
[4,5].each |Int i| { ["a","b","c"].each |Str s| { r.add([i,s]) } }
From a List Produce a List of Duplicate Entries
Taking a list:
Write the code to produce a list of duplicates in the list:
["andrew", "bob", "chris", "bob"]
Write the code to produce a list of duplicates in the list:
["bob"]
php
$arr = array('andrew', 'bob', 'chris', 'bob', 'chris', 'john', 'mary', 'lucy');
function match($a, $b)
{
// This is a separate function so you could include checking
// with loose comparisons or lowercase both strings, etc.
return $a === $b;
}
$results = array();
sort($arr);
for($i = 0; $i < count($arr) - 1; $i++)
{
if (match($arr[$i], $arr[$i+1]))
{
$results[] = $arr[$i];
$i++;
}
}
print_r($results);
function match($a, $b)
{
// This is a separate function so you could include checking
// with loose comparisons or lowercase both strings, etc.
return $a === $b;
}
$results = array();
sort($arr);
for($i = 0; $i < count($arr) - 1; $i++)
{
if (match($arr[$i], $arr[$i+1]))
{
$results[] = $arr[$i];
$i++;
}
}
print_r($results);
$arr = array('lucy', 'andrew', 'lucy', 'bob', 'chris', 'bob', 'chris', 'john', 'mary');
function match($a, $b)
{
// This is a separate function so you could include checking
// with loose comparisons or lowercase both strings, etc.
return $a === $b;
}
$results = array();
for($i = 0; $i < count($arr); $i++)
{
if (isset($results[$arr[$i]]))
{
$results[$arr[$i]]++;
}
else
{
$results[$arr[$i]] = 0;
}
}
$out = array();
foreach($results as $name => $count)
{
echo $name . ':' . $count . '<br />';
if ($count > 0)
{
$out[] = $name;
}
}
print_r($out);
function match($a, $b)
{
// This is a separate function so you could include checking
// with loose comparisons or lowercase both strings, etc.
return $a === $b;
}
$results = array();
for($i = 0; $i < count($arr); $i++)
{
if (isset($results[$arr[$i]]))
{
$results[$arr[$i]]++;
}
else
{
$results[$arr[$i]] = 0;
}
}
$out = array();
foreach($results as $name => $count)
{
echo $name . ':' . $count . '<br />';
if ($count > 0)
{
$out[] = $name;
}
}
print_r($out);
<?php
$array = array("andrew", "bob", "chris", "bob");
$counts = array_count_values($array);
$duplicates = array_filter(
array_unique($array),
function($key) use ($counts) {
return $counts[$key] > 1;
}
);
?>
$array = array("andrew", "bob", "chris", "bob");
$counts = array_count_values($array);
$duplicates = array_filter(
array_unique($array),
function($key) use ($counts) {
return $counts[$key] > 1;
}
);
?>
clojure
(->> '("andrew" "bob" "chris" "bob")
(group-by identity)
(filter #(> (count (second %)) 1))
(map first))
(group-by identity)
(filter #(> (count (second %)) 1))
(map first))
fantom
nameCounts := Str:Int[:] { def = 0 }
["andrew", "bob", "chris", "bob"].each |Str v| { nameCounts[v]++ }
results := nameCounts.findAll |Int v, Str k->Bool| { v > 1 }.keys
echo(results.join(","))
["andrew", "bob", "chris", "bob"].each |Str v| { nameCounts[v]++ }
results := nameCounts.findAll |Int v, Str k->Bool| { v > 1 }.keys
echo(results.join(","))
Fetch an element of a list by index
Given the list
[One, Two, Three, Four, Five], fetch the third element ('Three')
php
$list = array("One", "Two", "Three", "Four", "Five");
$three = $list[2];
$three = $list[2];
clojure
(nth '[One Two Three Four Five] 2)
fantom
["One", "Two", "Three", "Four", "Five"][2]
["One", "Two", "Three", "Four", "Five"].get(2)
Fetch the last element of a list
Given the list
[Red, Green, Blue], access the last element ('Blue')
php
$list = array("Red", "Green", "Blue");
$last = array_pop($list);
// Be aware of that $list only contains two elements now - not three
$last = array_pop($list);
// Be aware of that $list only contains two elements now - not three
$list = array("Red", "Green", "Blue");
$last = $list[count($list)-1];
$last = $list[count($list)-1];
clojure
(last '[One Two Three Four Five])
fantom
["Red", "Green", "Blue"][-1]
["One", "Two", "Three", "Four", "Five"].last
Find the common items in two lists
Given two lists, find the common items. E.g. given beans =
['broad', 'mung', 'black', 'red', 'white'] and colors = ['black', 'red', 'blue', 'green'], what are the bean varieties that are also color names?
php
$result = array_intersect($beans, $colors);
sort($result); // just to clean it up :)
sort($result); // just to clean it up :)
clojure
(use 'clojure.set)
(let [beans '[broad mung black red white]
colors '[black red blue green]]
(intersection (set beans) (set colors)))
(let [beans '[broad mung black red white]
colors '[black red blue green]]
(intersection (set beans) (set colors)))
fantom
beans := ["broad", "mung", "black", "red", "white"]
colors := ["black", "red", "blue", "green"]
echo(beans.intersection(colors))
colors := ["black", "red", "blue", "green"]
echo(beans.intersection(colors))
Display the unique items in a list
Display the unique items in a list, e.g. given ages =
[18, 16, 17, 18, 16, 19, 14, 17, 19, 18], display the unique elements, i.e. with duplicates removed.
php
$ages = array(18, 16, 17, 18, 16, 19, 14, 17, 19, 18);
$ages = array_unique($ages);
// be aware of that $ages[6] will print 14
$ages = array_unique($ages);
// be aware of that $ages[6] will print 14
clojure
;; returns a set
(set [18, 16, 17, 18, 16, 19, 14, 17, 19, 18])
;;#{14 16 17 18 19}
;; returns a lazy sequence of the unique elements
(distinct [18, 16, 17, 18, 16, 19, 14, 17, 19, 18])
;;(18 16 17 19 14)
(set [18, 16, 17, 18, 16, 19, 14, 17, 19, 18])
;;#{14 16 17 18 19}
;; returns a lazy sequence of the unique elements
(distinct [18, 16, 17, 18, 16, 19, 14, 17, 19, 18])
;;(18 16 17 19 14)
fantom
uniqueAges := [18, 16, 17, 18, 16, 19, 14, 17, 19, 18].unique
echo(uniqueAges)
echo(uniqueAges)
Remove an element from a list by index
Given the list
[Apple, Banana, Carrot], remove the first element to produce the list [Banana, Carrot]
php
$list = array("Apple", "Banana", "Carrot");
unset($list[0]);
// Be aware of that $list[0] isn't set. "Banana" is still $list[1]
unset($list[0]);
// Be aware of that $list[0] isn't set. "Banana" is still $list[1]
$list = array("Apple", "Banana", "Carrot");
array_shift($list);
// Be aware of that $list[0] is set to "Banana"
array_shift($list);
// Be aware of that $list[0] is set to "Banana"
clojure
(let [fruit ["Apple" "Banana" "Carrot"]
index 0]
(concat
(take index fruit)
(drop (+ index 1) fruit)))
index 0]
(concat
(take index fruit)
(drop (+ index 1) fruit)))
fantom
list := ["Apple", "Banana", "Carrot"]
list.removeAt(0)
list.removeAt(0)
Remove the last element of a list
php
$list = array("Apple", "Banana", "Carrot");
unset($list[count($list)-1]);
// Be aware of that
// $list[] = "Orange";
// will be $list[3] and not $list[2]
unset($list[count($list)-1]);
// Be aware of that
// $list[] = "Orange";
// will be $list[3] and not $list[2]
$list = array("Apple", "Banana", "Carrot");
array_pop($list);
array_pop($list);
clojure
(pop ["Apple" "Banana" "Carrot"])
fantom
list := ["Apple", "Banana", "Carrot"]
list.removeAt(-1)
list.removeAt(-1)
list := ["Apple", "Banana", "Carrot"]¨
list.pop
list.pop
Rotate a list
Given a list
["apple", "orange", "grapes", "bananas"], rotate it by removing the first item and placing it on the end to yield ["orange", "grapes", "bananas", "apple"]
php
$list = array("Apple", "Orange", "Grapes", "Banana");
$first = array_shift($list); //get and remove the first
array_push($list, $first); //prepend the $first to the array
$first = array_shift($list); //get and remove the first
array_push($list, $first); //prepend the $first to the array
clojure
(let [fruit ["apple" "orange" "grapes" "bananas"]]
(concat (rest fruit) [(first fruit)])
(concat (rest fruit) [(first fruit)])
fantom
list := ["apple", "orange", "grapes", "bananas"]
list.add(list.removeAt(0))
list.add(list.removeAt(0))
Gather together corresponding elements from multiple lists
Given several lists, gather together the first element from every list, the second element from every list, and so on for all corresponding index values in the lists. E.g. for these three lists, first =
['Bruce', 'Tommy Lee', 'Bruce'], last = ['Willis', 'Jones', 'Lee'], years = [1955, 1946, 1940] the result should produce 3 actors. The middle actor should be Tommy Lee Jones.
php
for ($i = 0; $i < $count; $i++) {
$list[] = array($first[$i], $last[$i], $years[$i]);
}
$list[] = array($first[$i], $last[$i], $years[$i]);
}
$list = array_map(NULL, $first, $last, $years);
clojure
(defn gatherer [listOfLists]
(if (empty? (first listOfLists))
() ; the base case for recursion
(cons
(map first listOfLists) ; get the first element of each of the lists
(gatherer (map rest listOfLists)) ; gather all the subsequent ones
)
)
)
(def firstnames '("Bruce" "Tommy Lee" "Bruce"))
(def lastnames '("Willis" "Jones" "Lee"))
(def years '(1955 1946 1940))
(println (gatherer [firstnames lastnames years]))
; -> ((Bruce Willis 1955) (Tommy Lee Jones 1946) (Bruce Lee 1940))
(if (empty? (first listOfLists))
() ; the base case for recursion
(cons
(map first listOfLists) ; get the first element of each of the lists
(gatherer (map rest listOfLists)) ; gather all the subsequent ones
)
)
)
(def firstnames '("Bruce" "Tommy Lee" "Bruce"))
(def lastnames '("Willis" "Jones" "Lee"))
(def years '(1955 1946 1940))
(println (gatherer [firstnames lastnames years]))
; -> ((Bruce Willis 1955) (Tommy Lee Jones 1946) (Bruce Lee 1940))
(def firstnames ["Bruce" "Tommy Lee" "Bruce"])
(def lastnames ["Willis" "Jones" "Lee"])
(def years [1955 1946 1940])
(println (map (fn [f l y] [f l y]) firstnames lastnames years))
(def lastnames ["Willis" "Jones" "Lee"])
(def years [1955 1946 1940])
(println (map (fn [f l y] [f l y]) firstnames lastnames years))
fantom
r := [,]
first.size.times |Int i| { r.add([first[i], last[i], years[i]]) }
echo(r)
first.size.times |Int i| { r.add([first[i], last[i], years[i]]) }
echo(r)
List Combinations
Given two source lists (or sets), generate a list (or set) of all the pairs derived by combining elements from the individual lists (sets). E.g. given suites =
['H', 'D', 'C', 'S'] and faces = ['2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K', 'A'], generate the deck of 52 cards, confirm the deck size and check it contains an expected card, say 'Ace of Hearts'.
php
foreach ($suites as $suite) {
foreach ($faces as $face) {
$cards[] = $suite.$face;
}
}
if (count($cards) == 52) {
echo "The deck have all 52 cards.\n";
}
if (in_array("HA", $cards)) {
echo "The deck contains 'Ace of Heart'\n";
} else {
echo "The deck doesn't contain 'Ace of Heart'\n";
}
foreach ($faces as $face) {
$cards[] = $suite.$face;
}
}
if (count($cards) == 52) {
echo "The deck have all 52 cards.\n";
}
if (in_array("HA", $cards)) {
echo "The deck contains 'Ace of Heart'\n";
} else {
echo "The deck doesn't contain 'Ace of Heart'\n";
}
clojure
(def suites ["H" "D" "C" "S"])
(def faces [2 3 4 5 6 7 8 9 10 "J" "Q" "K" "A"])
(defn listCards [] (for [s suites f faces] [f s]))
(some (partial = ["A" "H"]) (listCards))
; -> true
(count (listCards))
; -> 52
(def faces [2 3 4 5 6 7 8 9 10 "J" "Q" "K" "A"])
(defn listCards [] (for [s suites f faces] [f s]))
(some (partial = ["A" "H"]) (listCards))
; -> true
(count (listCards))
; -> 52
fantom
r := [,]
["2","3","4","5","6","7","8","9","10","J","Q","K","A"].each |Str c|
{ ["H","D","C","S"].each |Str s| { r.add([c,s]) } }
q := ["A","H"]
result := r.contains(q)
echo("Deck size=${r.size}, contains $q? -> $result")
["2","3","4","5","6","7","8","9","10","J","Q","K","A"].each |Str c|
{ ["H","D","C","S"].each |Str s| { r.add([c,s]) } }
q := ["A","H"]
result := r.contains(q)
echo("Deck size=${r.size}, contains $q? -> $result")
Perform an operation on every item of a list
Perform an operation on every item of a list, e.g.
for the list
the list of sizes of the strings, e.g.
for the list
["ox", "cat", "deer", "whale"] calculate
the list of sizes of the strings, e.g.
[2, 3, 4, 5]
php
$sizes = array_map('strlen', array('ox', 'cat', 'deer', 'whale'));
clojure
(map count ["ox" "cat" "deer" "whale"])
fantom
["ox", "cat", "deer", "whale"].map { it.size }
Split a list of things into numbers and non-numbers
Given a list that might contain e.g. a string, an integer, a float and a date,
split the list into numbers and non-numbers.
split the list into numbers and non-numbers.
php
$now = new DateTime();
$things = array('hello', 25, 3.14, $now);
$numbers = array_filter($things, 'is_numeric');
$others = array();
foreach ($things as $thing) {
if (!in_array($thing, $numbers)) {
$others[] = $thing;
}
}
$things = array('hello', 25, 3.14, $now);
$numbers = array_filter($things, 'is_numeric');
$others = array();
foreach ($things as $thing) {
if (!in_array($thing, $numbers)) {
$others[] = $thing;
}
}
clojure
(def jumble [3 "Bill" 5.7 '("A" "B" "C")]) ; int, string, float, list
(defn numberNonNumberSorter [jumbledList]
(if (empty? jumbledList)
(hash-map :numbers [], :nonnumbers []) ; recursion base case - return two empty lists
(let [head (first jumbledList)] ; let <head> be the first element in the list
(let [tailresult (numberNonNumberSorter (rest jumbledList))] ; tailresult applies recursively to the remainder
(if (number? head) ; is head a number?
(hash-map
:numbers (cons head (tailresult :numbers)) ; add <head> to the numbers
:nonnumbers (tailresult :nonnumbers)) ; leave nonnumbers the same
(hash-map
:numbers (tailresult :numbers) ; leave numbers the same
:nonnumbers (cons head (tailresult :nonnumbers))) ; add <head> to nonnumbers
)
)
)
)
)
(println (numberNonNumberSorter jumble))
; -> {:nonnumbers (Bill (A B C)), :numbers (3 5.7)}
(defn numberNonNumberSorter [jumbledList]
(if (empty? jumbledList)
(hash-map :numbers [], :nonnumbers []) ; recursion base case - return two empty lists
(let [head (first jumbledList)] ; let <head> be the first element in the list
(let [tailresult (numberNonNumberSorter (rest jumbledList))] ; tailresult applies recursively to the remainder
(if (number? head) ; is head a number?
(hash-map
:numbers (cons head (tailresult :numbers)) ; add <head> to the numbers
:nonnumbers (tailresult :nonnumbers)) ; leave nonnumbers the same
(hash-map
:numbers (tailresult :numbers) ; leave numbers the same
:nonnumbers (cons head (tailresult :nonnumbers))) ; add <head> to nonnumbers
)
)
)
)
)
(println (numberNonNumberSorter jumble))
; -> {:nonnumbers (Bill (A B C)), :numbers (3 5.7)}
(group-by number? ["hello" 42 3.14 (Date.)])
fantom
things := ["hello", 25, 3.14, Time.now]
numbers := things.findType(Num#)
nonNumbers := things.exclude { numbers.contains(it) }
numbers := things.findType(Num#)
nonNumbers := things.exclude { numbers.contains(it) }
Test if a condition holds for all items of a list
Given a list, test if a certain logical condition (i.e. predicate) holds for all items of the list.
clojure
(every? #(> % 1) [2 3 4])
fantom
echo([2,3,4].all{ it>1 })
Test if a condition holds for any items of a list
Given a list, test if a certain logical condition (i.e. predicate) holds for any items of the list.
clojure
; The standard library in Clojure has "not-any?" but (oddly enough) no "any?"
(defn any? [pred coll]
((complement not-any?) pred coll))
(any? #(> % 3) [2 3 4])
(defn any? [pred coll]
((complement not-any?) pred coll))
(any? #(> % 3) [2 3 4])
(some #(> % 3) [2 3 4])
fantom
echo([2,3,4].any{ it==4 })
Define an empty map
php
$map = array();
$map = array("" => "");
clojure
(def m {})
fantom
map := [:]
Define an unmodifiable empty map
php
/* It's not possible to define an array as a constant
* Instead we can use the serialize-function */
$fruits = array("apple", "banana", "orange");
define("FRUITS", serialize($fruits));
echo FRUITS; // a:3:{i:0;s:5:"apple";i:1;s:6:"banana";i:2;s:6:"orange";}
$my_fruits = unserialize(FRUITS); // and normal array again
* Instead we can use the serialize-function */
$fruits = array("apple", "banana", "orange");
define("FRUITS", serialize($fruits));
echo FRUITS; // a:3:{i:0;s:5:"apple";i:1;s:6:"banana";i:2;s:6:"orange";}
$my_fruits = unserialize(FRUITS); // and normal array again
clojure
; Clojure maps are immutable
(def m {})
(def m {})
fantom
map := [:].ro
Define an initial map
Define the map
{circle:1, triangle:3, square:4}
php
$map = array("circle" => 1, "triangle" => 3, "square" => 4);
clojure
(def m '{circle 1 triangle 1 square 4})
fantom
map := ["circle":1, "triangle":2, "square":4]
Check if a key exists in a map
Given a map pets
{joe:cat,mary:turtle,bill:canary} print "ok" if an pet exists for "mary"
php
if (array_key_exists("mary", $pets)) {
echo "ok";
}
echo "ok";
}
if (isset($pets["mary"])) { // only works if $pets["mary"] can't be false or 0
echo "ok";
}
echo "ok";
}
clojure
(if (contains? '{joe cat mary turtle bill canary} 'mary)
(println "ok"))
(println "ok"))
fantom
map := ["joe":"cat", "mary":"turtle", "bill":"canary"]
if (map.containsKey("mary")) echo("ok")
if (map.containsKey("mary")) echo("ok")
Retrieve a value from a map
Given a map pets
{joe:cat,mary:turtle,bill:canary} print the pet for "joe" ("cat")
php
echo $pets["joe"];
clojure
(def pets '{joe cat mary turtle bill canary})
(println (get pets 'joe))
(println (get pets 'joe))
fantom
map := ["joe":"cat", "mary":"turtle", "bill":"canary"]
pet := map["joe"]
echo("pet=$pet")
pet := map["joe"]
echo("pet=$pet")
Add an entry to a map
Given an empty pets map, add the mapping from
"rob" to "dog"
php
$pets["rob"] = "dog";
clojure
(assoc {} 'rob 'dog)
fantom
map["rob"] = "dog"
Remove an entry from a map
Given a map pets
{joe:cat,mary:turtle,bill:canary} remove the mapping for "bill" and print "canary"
php
$last = array_pop($pets); // removes last key and assign it to the variable
echo $last;
echo $last;
$last = $pets[count($pets)-1];
echo $last;
unset($last);
echo $last;
unset($last);
$bill = $pets["bill"];
echo $bill;
unset($bill);
echo $bill;
unset($bill);
print_r(array_pop($pets));
clojure
; Maps are immutable
; The following expression will return a new map without the 'bill key
(let [pets '{joe cat mary turtle bill canary}]
(println (get pets 'bill))
(dissoc pets 'bill))
; The following expression will return a new map without the 'bill key
(let [pets '{joe cat mary turtle bill canary}]
(println (get pets 'bill))
(dissoc pets 'bill))
fantom
pet := map.remove("bill")
echo ("pet=$pet")
echo ("pet=$pet")
Create a histogram map from a list
Given the list
[a,b,a,c,b,b], produce a map {a:2, b:3, c:1} which contains the count of each unique item in the list
php
$list = array("a","b","a","c","b","b");
$map = array_count_values($list);
$map = array_count_values($list);
clojure
(let [l '[a b a c b b]]
(loop [m {}
d (distinct l)]
(let [item (first d)]
(if (zero? (count d))
m
(recur
(assoc m
item
(count
(filter #(= item %) l)))
(rest d))))))
(loop [m {}
d (distinct l)]
(let [item (first d)]
(if (zero? (count d))
m
(recur
(assoc m
item
(count
(filter #(= item %) l)))
(rest d))))))
(->> [:a :b :a :c :b :b]
(group-by identity)
(reduce (fn [m e] (assoc m (first e) (count (second e)))) {}))
(group-by identity)
(reduce (fn [m e] (assoc m (first e) (count (second e)))) {}))
(reduce conj {} (for [[x xs] (group-by identity "abacbb")] [x (count xs)]))
(frequencies ["a","b","a","c","b","b"])
(frequencies '[a b a c b b])
fantom
list := ["a","b","a","c","b","b"]
map := [Str:Int][:]
list.each |Str s, Int i| { if(!map.containsKey(s)) map.add(s,1); else map[s] = ++map[s] }
echo (map)
map := [Str:Int][:]
list.each |Str s, Int i| { if(!map.containsKey(s)) map.add(s,1); else map[s] = ++map[s] }
echo (map)
Categorise a list
Given the list
[one, two, three, four, five] produce a map {3:[one, two], 4:[four, five], 5:[three]} which sorts elements into map entries based on their length
php
foreach ($array as $m) {
$l = strlen($m);
$map[$l][] = $m;
}
arsort($map);
$l = strlen($m);
$map[$l][] = $m;
}
arsort($map);
clojure
(loop [m {}
l ["one" "two" "three" "four" "five"]]
(if (zero? (count l))
m
(let [item (first l)
key (count item)]
(recur
(assoc m key (cons item (get m key [])))
(rest l)))))
l ["one" "two" "three" "four" "five"]]
(if (zero? (count l))
m
(let [item (first l)
key (count item)]
(recur
(assoc m key (cons item (get m key [])))
(rest l)))))
(group-by count ["one" "two" "three" "four" "five"])
fantom
list := ["one", "two", "three", "four", "five"]
map := [Int:List][:]
list.each { List l := map[it.size] ?: [,]; map[it.size] = l.add(it) }
echo(map)
map := [Int:List][:]
list.each { List l := map[it.size] ?: [,]; map[it.size] = l.add(it) }
echo(map)
Perform an action if a condition is true (IF .. THEN)
Given a variable name, if the value is
"Bob", display the string "Hello, Bob!". Perform no action if the name is not equal.
php
if($name == "Bob") {
echo "Hello, Bob!";
}
echo "Hello, Bob!";
}
clojure
(def person "Bob")
(if (= person "Bob")
(println "Hello, Bob!"))
(if (= person "Bob")
(println "Hello, Bob!"))
fantom
if (name=="Bob") echo("Hello, Bob!")
Perform different actions depending on a boolean condition (IF .. THEN .. ELSE)
Given a variable age, if the value is greater than 42 display
"You are old", otherwise display "You are young"
php
if($age < 42) {
echo "You are young";
} else {
echo "You are old";
}
echo "You are young";
} else {
echo "You are old";
}
echo "You are " . (($age < 43) ? "young" : "old");
clojure
(def age 41)
(if (> age 42) "You are old" "You are young")
(if (> age 42) "You are old" "You are young")
fantom
if (age > 42)
echo("You are old")
else
echo("You are young")
echo("You are old")
else
echo("You are young")
echo((age > 42) ? "You are old" : "You are young")
Perform different actions depending on several boolean conditions (IF .. THEN .. ELSIF .. ELSE)
php
echo "You are " . (($age > 84) ? "really ancient" : (($age > 30) ? "middle-aged" : "young"));
$response = "You are ";
if ($age > 84) {
$response .= "really ancient";
} else if ($age > 30) {
$response .= "middle-aged";
} else {
$response .= "young";
}
echo $response;
if ($age > 84) {
$response .= "really ancient";
} else if ($age > 30) {
$response .= "middle-aged";
} else {
$response .= "young";
}
echo $response;
clojure
(println
(condp <= age
84 "You are really ancient"
30 "You are middle aged"
"You are young"))
(condp <= age
84 "You are really ancient"
30 "You are middle aged"
"You are young"))
fantom
if (age > 84)
echo("You are really ancient")
else if (age > 30)
echo("You are middle-aged")
else
echo("You are young")
echo("You are really ancient")
else if (age > 30)
echo("You are middle-aged")
else
echo("You are young")
Replacing a conditional with many branches with a switch/case statement
Many languages support more compact forms of branching than just if ... then ... else such as switch or case or match. Use such a form to add an appropriate placing suffix to the numbers 1..40, e.g. 1st, 2nd, 3rd, 4th, ..., 11th, 12th, ... 39th, 40th
php
function suffix($n) {
switch ($n) {
case ($n % 100 >= 4) && ($n % 100 <= 20):
return 'th';
case $n % 10 == 1:
return 'st';
case $n % 10 == 2:
return 'nd';
case $n % 10 == 3:
return 'rd';
default:
return 'th';
}
}
for ($n=1; $n<=40; $n++) {
echo $n . suffix($n) ."\n";
}
switch ($n) {
case ($n % 100 >= 4) && ($n % 100 <= 20):
return 'th';
case $n % 10 == 1:
return 'st';
case $n % 10 == 2:
return 'nd';
case $n % 10 == 3:
return 'rd';
default:
return 'th';
}
}
for ($n=1; $n<=40; $n++) {
echo $n . suffix($n) ."\n";
}
clojure
(def n 112)
(println (str n
(let [rem (mod n 100)]
(if (and (>= rem 11) (<= rem 13))
"th"
(condp = (mod n 10)
1 "st"
2 "nd"
3 "rd"
"th")))))
(println (str n
(let [rem (mod n 100)]
(if (and (>= rem 11) (<= rem 13))
"th"
(condp = (mod n 10)
1 "st"
2 "nd"
3 "rd"
"th")))))
fantom
suffix := |Int n -> Str|
{
if ((4..20).contains(n % 100))
return "th"
switch((n.toStr)[-1])
{
case '1': return "st"
case '2': return "nd"
case '3': return "rd"
default: return "th"
}
}
(1..40).each { echo("$it${suffix(it)}") }
{
if ((4..20).contains(n % 100))
return "th"
switch((n.toStr)[-1])
{
case '1': return "st"
case '2': return "nd"
case '3': return "rd"
default: return "th"
}
}
(1..40).each { echo("$it${suffix(it)}") }
Perform an action multiple times based on a boolean condition, checked before the first action (WHILE .. DO)
Starting with a variable x=1, Print the sequence
"1,2,4,8,16,32,64,128," by doubling x and checking that x is less than 150.
php
$x = 1;
while($x < 150) {
echo "$x,";
$x *= 2;
}
while($x < 150) {
echo "$x,";
$x *= 2;
}
$x = 0;
$c = pow(2, $x);
while($c < 150) {
echo "$c,";
$c = pow(2, $x++);
}
$c = pow(2, $x);
while($c < 150) {
echo "$c,";
$c = pow(2, $x++);
}
clojure
(take-while #(< % 150) (iterate #(* 2 %) 1))
fantom
x := 1
while (x < 150) {
Env.cur.out.print("$x,")
x *= 2
}
echo
while (x < 150) {
Env.cur.out.print("$x,")
x *= 2
}
echo
Perform an action multiple times based on a boolean condition, checked after the first action (DO .. WHILE)
Simulate rolling a die until you get a six. Produce random numbers, printing them until a six is rolled. An example output might be
"4,2,1,2,6"
php
do {
$rand = rand(1,6);
echo $rand;
if ($rand != 6) echo ", ";
} while ($rand != 6);
$rand = rand(1,6);
echo $rand;
if ($rand != 6) echo ", ";
} while ($rand != 6);
clojure
(loop [r (rand-int 6)]
(if (= r 5)
nil
(do
(println r)
(recur (rand-int 6)))))
(if (= r 5)
nil
(do
(println r)
(recur (rand-int 6)))))
fantom
rnd := 0
while(rnd != 6) {
rnd = Int.random(1..6)
Env.cur.out.print(rnd)
if (rnd != 6)
Env.cur.out.print(",")
}
echo
while(rnd != 6) {
rnd = Int.random(1..6)
Env.cur.out.print(rnd)
if (rnd != 6)
Env.cur.out.print(",")
}
echo
Perform an action a fixed number of times (FOR)
Display the string
"Hello" five times like "HelloHelloHelloHelloHello"
php
for($i = 0; $i < 5; $i++) {
echo "Hello";
}
echo "Hello";
}
clojure
(dotimes [_ 5]
(print "Hello"))
(print "Hello"))
fantom
5.times { Env.cur.out.print("Hello") }
for (i := 0; i < 5; i++)
Env.cur.out.print("Hello")
Env.cur.out.print("Hello")
(1..5).each { Env.cur.out.print("Hello") }
Perform an action a fixed number of times with a counter
Display the string
"10 .. 9 .. 8 .. 7 .. 6 .. 5 .. 4 .. 3 .. 2 .. 1 .. Liftoff!"
php
for($i = 10; $i > 0; $i--) {
echo $i." .. ";
}
echo "Liftoff!";
echo $i." .. ";
}
echo "Liftoff!";
clojure
(dotimes [i 10]
(print (str (- 10 i) " .. ")))
(println "Liftoff!")
(print (str (- 10 i) " .. ")))
(println "Liftoff!")
fantom
(10..1).each { Env.cur.out.print("$it .. ") }
Env.cur.out.print("Liftoff!")
Env.cur.out.print("Liftoff!")
for (i := 10; i >= 1; i--)
Env.cur.out.print("$i .. ")
Env.cur.out.print("Liftoff!")
Env.cur.out.print("$i .. ")
Env.cur.out.print("Liftoff!")
Read the contents of a file into a string
php
$file_contents = file_get_contents("file.txt");
clojure
(slurp "/tmp/foobar")
fantom
contents := File(`file.text`).readAllStr
Process a file one line at a time
Open the source file to your solution and print each line in the file, prefixed by the line number, like:
1> First line of file
2> Second line of file
3> Third line of file
1> First line of file
2> Second line of file
3> Third line of file
php
$lines = file('file.txt');
foreach ($lines as $lnum => $line) {
echo $line_num."> ".$line; // you may want to add a <br />\n
}
foreach ($lines as $lnum => $line) {
echo $line_num."> ".$line; // you may want to add a <br />\n
}
<?php
$lines = new SplFileObject('file.txt');
foreach ($lines as $line) {
echo $line;
}
?>
$lines = new SplFileObject('file.txt');
foreach ($lines as $line) {
echo $line;
}
?>
clojure
(defn read-line-by-line [fn]
(reduce str (map (partial format "%d> %s\n")
(iterate inc 1)
(read-lines fn))))
(reduce str (map (partial format "%d> %s\n")
(iterate inc 1)
(read-lines fn))))
fantom
File(`input.text`).readAllLines.each |Str s, Int i| { echo("${i+1}> $s") }
Write a string to a file
php
/****
* For some (security)reason I couldn't
* submit this without adding a space to
* the functionnames. Please remove it :)
****/
if ($fh = f open("file.txt", 'w')) {
f write($fh, "Some text\n");
f close($fh);
}
* For some (security)reason I couldn't
* submit this without adding a space to
* the functionnames. Please remove it :)
****/
if ($fh = f open("file.txt", 'w')) {
f write($fh, "Some text\n");
f close($fh);
}
<?php
file_put_contents('file.txt', 'a string');
?>
file_put_contents('file.txt', 'a string');
?>
clojure
(with-out-writer "output.txt" (println "Hello file!"))
fantom
File(`out.txt`).out.writeChars("some text").flush
Append to a file
php
<?php
if ($fh = fopen("file.txt", 'a')) { // a == append
fwrite($fh, "Append some text\n");
fclose($fh);
}
?>
if ($fh = fopen("file.txt", 'a')) { // a == append
fwrite($fh, "Append some text\n");
fclose($fh);
}
?>
<?php
file_put_contents('file.txt', 'a string to append', FILE_APPEND);
?>
file_put_contents('file.txt', 'a string to append', FILE_APPEND);
?>
clojure
(with-out-append-writer "output.txt" (println "This is appended to the file"))
fantom
File(`out.txt`).out(true).writeChars("some text").flush
Process each file in a directory
php
if ($dh = opendir($dir)) { // if we have access
while (($file = readdir($dh)) !== false) { // as long as there is a file
echo "name: $file\n"; // echo its name
}
closedir($dh); // close the dir
}
while (($file = readdir($dh)) !== false) { // as long as there is a file
echo "name: $file\n"; // echo its name
}
closedir($dh); // close the dir
}
clojure
; (defn process-file [f] "process one file" body...)
(map process-file (.listFiles (File. ".")))
(map process-file (.listFiles (File. ".")))
fantom
File(`./`).list.each { process(it) }
Process each file in a directory recursively
php
if ($dir_handle = opendir($dir))
list_dir($dir_handle);
function list_dir($dh) {
// as long as we can read the dir
while (($file = readdir($dh)) !== false) {
// if it's a dir and it's not the current dir nor the above dir
if (is_dir($file) && $file != '.' && $file !='..') {
// open the dir, print it's name and all files inside
$handle = opendir($file);
echo $file."\n";
list_dir($handle);
// if it's a simple file
} else if ($file != '.' && $file !='..') {
// type it's name
echo $file."\n";
}
}
closedir($dir_handle); // close the dirs
}
if ($dir_handle = opendir($dir))
list_dir($dir_handle);
function list_dir($dh) {
// as long as we can read the dir
while (($file = readdir($dh)) !== false) {
// if it's a dir and it's not the current dir nor the above dir
if (is_dir($file) && $file != '.' && $file !='..') {
// open the dir, print it's name and all files inside
$handle = opendir($file);
echo $file."\n";
list_dir($handle);
// if it's a simple file
} else if ($file != '.' && $file !='..') {
// type it's name
echo $file."\n";
}
}
closedir($dir_handle); // close the dirs
}
clojure
; (defn process-file [f] "process one file" body...)
(map process-file (file-seq (File. ".")))
(map process-file (file-seq (File. ".")))
fantom
File(`./`).walk { process(it) }
Parse a date and time from a string
Given the string
"2008-05-06 13:29", parse it as a date representing 6th March, 2008 1:29:00pm in the local time zone.
php
echo date("jS F, Y g:i:sa", strtotime("2008-05-06 13:29")); // small version
clojure
(.. (SimpleDateFormat. "yyyy-MM-dd HH:mm")
(parse "2008-05-06 13:29"))
(parse "2008-05-06 13:29"))
fantom
dt := DateTime.fromLocale("2008-05-06 13:29", "YYYY-MM-DD hh:mm")
Display information about a date
Display the day of month, day of year, month name and day name of the day 8 days from now.
php
$eightdays = strtotime("+8 days");
$dayofmonth = date("d", $eightdays); // 3
$dayofyear = date("z", $eightdays); // 183
$monthname = date("F", $eightdays); // July
$dayname = date("l", $eightdays); // Saturday
$dayofmonth = date("d", $eightdays); // 3
$dayofyear = date("z", $eightdays); // 183
$monthname = date("F", $eightdays); // July
$dayname = date("l", $eightdays); // Saturday
$eightdays = time() + 1 * 60 * 60 * 24 * 8;
$dayofmonth = date("d", $eightdays); // 3
$dayofyear = date("z", $eightdays); // 183
$monthname = date("F", $eightdays); // July
$dayname = date("l", $eightdays); // Saturday
$dayofmonth = date("d", $eightdays); // 3
$dayofyear = date("z", $eightdays); // 183
$monthname = date("F", $eightdays); // July
$dayname = date("l", $eightdays); // Saturday
clojure
(let [cal (Calendar/getInstance)]
(.add cal Calendar/DAY_OF_YEAR 8)
(println (.format (SimpleDateFormat. "d, D, MMMM, EEEE")
(.getTime cal))))
(.add cal Calendar/DAY_OF_YEAR 8)
(println (.format (SimpleDateFormat. "d, D, MMMM, EEEE")
(.getTime cal))))
fantom
date := Date.today + 8day
echo(date.day)
echo(date.dayOfYear)
echo(date.month.localeFull)
echo(date.weekday.localeFull)
echo(date.day)
echo(date.dayOfYear)
echo(date.month.localeFull)
echo(date.weekday.localeFull)
Display a date in different locales
Display a language/locale friendly version of New Year's Day for 2009 for several languages/locales. E.g. for languages English, French, German, Italian, Dutch the output might be something like:
Thursday, January 1, 2009
jeudi 1 janvier 2009
giovedì 1 gennaio 2009
Donnerstag, 1. Januar 2009
donderdag 1 januari 2009
(Indicate in comments where possible if any language specific or operating system configuration needs to be in place.)
Thursday, January 1, 2009
jeudi 1 janvier 2009
giovedì 1 gennaio 2009
Donnerstag, 1. Januar 2009
donderdag 1 januari 2009
(Indicate in comments where possible if any language specific or operating system configuration needs to be in place.)
php
/* Be aware of that you need to have the locales installed */
setlocale(LC_TIME, "en_US");
echo strftime("%A, %B %e, %Y%n"); // %n = \n in strftime()
setlocale(LC_TIME, "fr_FR"); // French
echo strftime("%A, %B %e, %Y%n");
setlocale(LC_TIME, "de_DE"); // German
echo strftime("%A, %B %e, %Y%n");
setlocale(LC_TIME, "it_IT"); // Italian
echo strftime("%A, %B %e, %Y%n");
setlocale(LC_TIME, "nl_NL", "nld_nld"); // Dutch; Unix and Windows
echo strftime("%A, %B %e, %Y%n");
setlocale(LC_TIME, "en_US");
echo strftime("%A, %B %e, %Y%n"); // %n = \n in strftime()
setlocale(LC_TIME, "fr_FR"); // French
echo strftime("%A, %B %e, %Y%n");
setlocale(LC_TIME, "de_DE"); // German
echo strftime("%A, %B %e, %Y%n");
setlocale(LC_TIME, "it_IT"); // Italian
echo strftime("%A, %B %e, %Y%n");
setlocale(LC_TIME, "nl_NL", "nld_nld"); // Dutch; Unix and Windows
echo strftime("%A, %B %e, %Y%n");
$locales = array("en_US", "fr_FR", "de_DE", "nl_NL", "it_IT");
foreach ($locales as $locale) {
setlocale(LC_TIME, $locale);
echo strftime("%A, %B %d %Y%n");
}
foreach ($locales as $locale) {
setlocale(LC_TIME, $locale);
echo strftime("%A, %B %d %Y%n");
}
clojure
(let [time (.getTime (GregorianCalendar. 2009 Calendar/JANUARY 1))]
(doseq [locale ["en" "fr" "it" "de" "nl"]]
(println (.format (DateFormat/getDateInstance DateFormat/FULL
(Locale. locale))
time))))
(doseq [locale ["en" "fr" "it" "de" "nl"]]
(println (.format (DateFormat/getDateInstance DateFormat/FULL
(Locale. locale))
time))))
fantom
// May require modification of Fantom distribution t
// for undefined locales - basically just create a '<locale-name>.props' plain text file with values like this:
// sunAbbr=Sun
// ..
// sunFull=Sunday
["en", "fr", "ru"].map { Locale(it) }.each |Locale l| {
l.use { echo(Date(2009, Month.jan, 1).toLocale("WWWW, MMMM D, YYYY")) }
}
// for undefined locales - basically just create a '<locale-name>.props' plain text file with values like this:
// sunAbbr=Sun
// ..
// sunFull=Sunday
["en", "fr", "ru"].map { Locale(it) }.each |Locale l| {
l.use { echo(Date(2009, Month.jan, 1).toLocale("WWWW, MMMM D, YYYY")) }
}
Display the current date and time
Create a Date object representing the current date and time. Print it out.
If you can also do this without creating a Date object you can show that too.
If you can also do this without creating a Date object you can show that too.
php
echo date('r') . "\n";
$d = new DateTime();
echo $d->format('r') . "\n";
$d = new DateTime();
echo $d->format('r') . "\n";
clojure
(import 'java.util.Date)
(println (str (Date.)))
(println (str (Date.)))
fantom
echo(DateTime.now)
Define a class
Declare a class named Greeter that takes a string on creation and greets using this string if you call the
"greet" method.
php
class Greeter {
private $whom;
public function __construct($whom) {
$this->whom = $whom;
}
public function greet() {
echo "Hello $this->whom.";
}
}
$g = new Greeter("Giacomo Girolamo");
$g->greet();
private $whom;
public function __construct($whom) {
$this->whom = $whom;
}
public function greet() {
echo "Hello $this->whom.";
}
}
$g = new Greeter("Giacomo Girolamo");
$g->greet();
clojure
(defprotocol IGreeter
(greet [this]))
(deftype Greeter [whom]
IGreeter
(greet [this]
(println (str "Hello, " whom))))
(greet (Greeter. "world"))
(greet [this]))
(deftype Greeter [whom]
IGreeter
(greet [this]
(println (str "Hello, " whom))))
(greet (Greeter. "world"))
(defn greeter [whom]
{:whom whom})
(defn greet [g]
(println (str "Hello, " (:whom g))))
(greet (greeter "world"))
{:whom whom})
(defn greet [g]
(println (str "Hello, " (:whom g))))
(greet (greeter "world"))
fantom
class Greeter
{
private Str whom
new make(Str whom) { this.whom = whom }
Void greet() { echo("Hello, $whom") }
}
Greeter("world").greet
{
private Str whom
new make(Str whom) { this.whom = whom }
Void greet() { echo("Hello, $whom") }
}
Greeter("world").greet
Instantiate object with mutable state
Reimplement the Greeter class so that the
For example, if the greetee is changed to
Hello, Tommy!
The getter would then be used to display the line:
I have just greeted Tommy.
'whom' property or data member remains private but is mutable, and is provided with getter and setter methods. Invoke the setter to change the greetee, invoke 'greet', then use the getter in displaying the line, "I have just greeted {whom}.".
For example, if the greetee is changed to
'Tommy' using the setter, the 'greet' method would display:
Hello, Tommy!
The getter would then be used to display the line:
I have just greeted Tommy.
php
class Greeter {
private $whom;
public function __construct($whom) {
$this->whom = $whom;
}
public function greet() {
echo "Hello $this->whom.\n";
}
public function getWhom() {
return $this->whom;
}
public function setWhom($whom) {
$this->whom = $whom;
}
}
$g = new Greeter("Giacomo Girolamo");
$g->greet();
$g->setWhom("Jean-Jaques");
$g->greet();
echo "I have just greeted " . $g->getWhom() . ".\n";
private $whom;
public function __construct($whom) {
$this->whom = $whom;
}
public function greet() {
echo "Hello $this->whom.\n";
}
public function getWhom() {
return $this->whom;
}
public function setWhom($whom) {
$this->whom = $whom;
}
}
$g = new Greeter("Giacomo Girolamo");
$g->greet();
$g->setWhom("Jean-Jaques");
$g->greet();
echo "I have just greeted " . $g->getWhom() . ".\n";
clojure
(defn greeter [whom]
(atom {:whom whom}))
(defn get-whom [g]
(:whom @g))
(defn set-whom [g whom]
(swap! g #(conj % {:whom whom})))
(defn greet [g]
(println (str "Hello, " (:whom @g) "!")))
; using the "class"
(let [g (greeter "world")]
(greet g)
(set-whom g "Tommy")
(greet g)
(println (str "I have just greeted " (get-whom g) ".")))
; or same effect without using any variables
(println (str "I have just greeted "
(get-whom (doto (greeter "world")
(greet)
(set-whom "Tommy")
(greet)))
"."))
(atom {:whom whom}))
(defn get-whom [g]
(:whom @g))
(defn set-whom [g whom]
(swap! g #(conj % {:whom whom})))
(defn greet [g]
(println (str "Hello, " (:whom @g) "!")))
; using the "class"
(let [g (greeter "world")]
(greet g)
(set-whom g "Tommy")
(greet g)
(println (str "I have just greeted " (get-whom g) ".")))
; or same effect without using any variables
(println (str "I have just greeted "
(get-whom (doto (greeter "world")
(greet)
(set-whom "Tommy")
(greet)))
"."))
fantom
class Greeter
{
new make(Str whom) { this.whom = whom }
Void greet() { echo("Hello, $whom!") }
Str whom
}
greeter := Greeter("world")
greeter.greet
greeter.whom = "Tommy"
echo("I have just greeted ${greeter.whom}.")
{
new make(Str whom) { this.whom = whom }
Void greet() { echo("Hello, $whom!") }
Str whom
}
greeter := Greeter("world")
greeter.greet
greeter.whom = "Tommy"
echo("I have just greeted ${greeter.whom}.")
Implement Inheritance Heirarchy
Implement a Shape abstract class which will form the base of an inheritance hierarchy that models 2D geometric shapes. It will have:
* A non-mutable
* A
* A
* A non-mutable
'name' property or data member set by derived or descendant classes at construction time
* A
'area' method intended to be overridden by derived or descendant classes ( double precision floating point return value)
* A
'print' method (also for overriding) will display the shape's name, area, and all shape-specific values
Two derived or descendant classes will be created:
* Circle -> Constructor requires a 'radius' argument, and a 'circumference' method to be implemented
* Rectangle -> Constructor requires 'length' and 'breadth' arguments, and a 'perimeter' method to be implemented
Instantiate an object of each class, and invoke each objects 'print' method to show relevant details.
php
<?php
abstract class Shape
{
protected $name;
abstract public function area ();
abstract public function _print ();
public function __construct ($name)
{
$this->name = $name;
}
}
class Circle extends Shape
{
protected $radius;
public function __construct ($radius)
{
parent::__construct('Circle');
$this->radius = $radius;
}
public function area ()
{
return pi() * $this->radius * $this->radius;
}
public function circumference ()
{
return 2 * pi() * $this->radius;
}
public function _print ()
{
print("I am a {$this->name} with ->\n");
print(" Radius: {$this->radius}\n");
print(" Area: {$this->area()}\n");
print(" Circumference {$this->circumference()}\n");
}
}
class Rectangle extends Shape
{
protected $length;
protected $breadth;
public function __construct ($length, $breadth)
{
parent::__construct('Rectangle');
$this->length = $length;
$this->breadth = $breadth;
}
public function area ()
{
return $this->length * $this->breadth;
}
public function perimeter ()
{
return (2 * $this->length) + (2 * $this->breadth);
}
public function _print ()
{
print("I am a {$this->name} with ->\n");
print(" Length, Width: {$this->length}, {$this->breadth}\n");
print(" Area: {$this->area()}\n");
print(" Perimeter: {$this->perimeter()}\n");
}
}
$shapes = array(new Circle(4.2) , new Rectangle(2.7, 3.1) , new Rectangle(6.2, 2.6) , new Circle(17.3));
foreach ($shapes as $shape) {
$shape->_print();
}
abstract class Shape
{
protected $name;
abstract public function area ();
abstract public function _print ();
public function __construct ($name)
{
$this->name = $name;
}
}
class Circle extends Shape
{
protected $radius;
public function __construct ($radius)
{
parent::__construct('Circle');
$this->radius = $radius;
}
public function area ()
{
return pi() * $this->radius * $this->radius;
}
public function circumference ()
{
return 2 * pi() * $this->radius;
}
public function _print ()
{
print("I am a {$this->name} with ->\n");
print(" Radius: {$this->radius}\n");
print(" Area: {$this->area()}\n");
print(" Circumference {$this->circumference()}\n");
}
}
class Rectangle extends Shape
{
protected $length;
protected $breadth;
public function __construct ($length, $breadth)
{
parent::__construct('Rectangle');
$this->length = $length;
$this->breadth = $breadth;
}
public function area ()
{
return $this->length * $this->breadth;
}
public function perimeter ()
{
return (2 * $this->length) + (2 * $this->breadth);
}
public function _print ()
{
print("I am a {$this->name} with ->\n");
print(" Length, Width: {$this->length}, {$this->breadth}\n");
print(" Area: {$this->area()}\n");
print(" Perimeter: {$this->perimeter()}\n");
}
}
$shapes = array(new Circle(4.2) , new Rectangle(2.7, 3.1) , new Rectangle(6.2, 2.6) , new Circle(17.3));
foreach ($shapes as $shape) {
$shape->_print();
}
clojure
(defmulti area :Shape)
(defmulti print :Shape)
; Circle methods
(defn circle [r]
{:Shape :Circle
:name "Circle"
:radius r})
(defn circumference [c]
(* 2 Math/PI (:radius c)))
(defmethod area :Circle [c]
(* Math/PI (:radius c) (:radius c)))
(defmethod print :Circle [c]
(println (format "I am a %s with ->" (:name c)))
(println (format "Radius: %.2f" (:radius c)))
(println (format "Area: %.2f" (area c)))
(println (format "Circumference: %.2f" (circumference c))))
; Rectangle methods
(defn rectangle [l b]
{:Shape :Rectangle
:name "Rectangle"
:length l
:breadth b})
(defn perimeter [r]
(+ (* 2 (:length r)) (* 2 (:breadth r))))
(defmethod area :Rectangle [r]
(* (:length r) (:breadth r)))
(defmethod print :Rectangle [r]
(println (format "I am a %s with ->" (:name r)))
(println (format "Length, Width: %.2f, %.2f" (:length r) (:breadth r)))
(println (format "Area: %.2f" (area r)))
(println (format "Perimeter: %.2f" (perimeter r))))
; usage of the "classes"
(let [shapes (list (circle 4.2) (rectangle 2.7 3.1) (rectangle 6.2 2.6) (circle 17.3))]
(doseq [shape shapes]
(print shape)))
(defmulti print :Shape)
; Circle methods
(defn circle [r]
{:Shape :Circle
:name "Circle"
:radius r})
(defn circumference [c]
(* 2 Math/PI (:radius c)))
(defmethod area :Circle [c]
(* Math/PI (:radius c) (:radius c)))
(defmethod print :Circle [c]
(println (format "I am a %s with ->" (:name c)))
(println (format "Radius: %.2f" (:radius c)))
(println (format "Area: %.2f" (area c)))
(println (format "Circumference: %.2f" (circumference c))))
; Rectangle methods
(defn rectangle [l b]
{:Shape :Rectangle
:name "Rectangle"
:length l
:breadth b})
(defn perimeter [r]
(+ (* 2 (:length r)) (* 2 (:breadth r))))
(defmethod area :Rectangle [r]
(* (:length r) (:breadth r)))
(defmethod print :Rectangle [r]
(println (format "I am a %s with ->" (:name r)))
(println (format "Length, Width: %.2f, %.2f" (:length r) (:breadth r)))
(println (format "Area: %.2f" (area r)))
(println (format "Perimeter: %.2f" (perimeter r))))
; usage of the "classes"
(let [shapes (list (circle 4.2) (rectangle 2.7 3.1) (rectangle 6.2 2.6) (circle 17.3))]
(doseq [shape shapes]
(print shape)))
fantom
abstract class Shape
{
const Str name
new make(Str name) { this.name = name }
abstract Float area()
abstract Void print()
}
class Circle : Shape
{
private Float radius
new make(Float radius) : super("circle") { this.radius = radius }
Float circumference() { return 2 * Float.pi * radius }
override Float area() { return Float.pi * radius.pow(2.0f) }
override Void print()
{
echo("I am a $name with radius $radius, area $area
and circumference $circumference")
}
}
class Rectangle : Shape
{
private Float length
private Float breadth
new make(Float length, Float breadth) : super("rectangle")
{
this.length = length
this.breadth = breadth
}
Float perimeter() { return 2 * (length + breadth) }
override Float area() { return length * breadth }
override Void print()
{
echo("I am a $name with length $length, breadth $breadth,
area $area and perimeter $perimeter")
}
}
circle := Circle(4.0f)
circle.print
rectangle := Rectangle(2.0f, 5.5f)
rectangle.print
{
const Str name
new make(Str name) { this.name = name }
abstract Float area()
abstract Void print()
}
class Circle : Shape
{
private Float radius
new make(Float radius) : super("circle") { this.radius = radius }
Float circumference() { return 2 * Float.pi * radius }
override Float area() { return Float.pi * radius.pow(2.0f) }
override Void print()
{
echo("I am a $name with radius $radius, area $area
and circumference $circumference")
}
}
class Rectangle : Shape
{
private Float length
private Float breadth
new make(Float length, Float breadth) : super("rectangle")
{
this.length = length
this.breadth = breadth
}
Float perimeter() { return 2 * (length + breadth) }
override Float area() { return length * breadth }
override Void print()
{
echo("I am a $name with length $length, breadth $breadth,
area $area and perimeter $perimeter")
}
}
circle := Circle(4.0f)
circle.print
rectangle := Rectangle(2.0f, 5.5f)
rectangle.print
Implement and use an Interface
Create a Serializable interface consisting of
* Accept a stream or handle or descriptor argument for the source or destination
* Save to destination or restore from source the properties or data members of the implementing class (restrict yourself to the primitive types
Next, create a Person class which has
'save' and 'restore' methods, each of which:
* Accept a stream or handle or descriptor argument for the source or destination
* Save to destination or restore from source the properties or data members of the implementing class (restrict yourself to the primitive types
'int' and 'string')
Next, create a Person class which has
'name' and 'age' properties or data members and implements this interface. Instantiate a Person object, save it to a serial stream, and instantiate a new Person object by restoring it from the serial stream.
php
class Person implements Serializable {
private $name;
private $age;
public function __construct($name, $age) {
$this->name = $name;
$this->age = $age;
}
public function serialize() {
return serialize(array($this->name, $this->age));
}
public function unserialize($serialized) {
list($this->name, $this->age) = unserialize($serialized);
}
public function getData() {
return array($this->name, $this->age);
}
}
$obj = new Person('Gaylord Focker', 21);
file_put_contents('person.dump', serialize($obj));
$newobj = unserialize(file_get_contents('person.dump'));
var_dump($newobj->getData());
private $name;
private $age;
public function __construct($name, $age) {
$this->name = $name;
$this->age = $age;
}
public function serialize() {
return serialize(array($this->name, $this->age));
}
public function unserialize($serialized) {
list($this->name, $this->age) = unserialize($serialized);
}
public function getData() {
return array($this->name, $this->age);
}
}
$obj = new Person('Gaylord Focker', 21);
file_put_contents('person.dump', serialize($obj));
$newobj = unserialize(file_get_contents('person.dump'));
var_dump($newobj->getData());
clojure
(defn person [name age]
{:name name :age age})
(defn show [p]
(println (format "Name=%s Age=%d" (:name p) (:age p))))
(defn save [p filename]
(with-out-writer filename (pr p)))
(defn restore [filename]
(read (PushbackReader. (reader filename))))
(let [p (person "Ken" 38)]
(show p)
(save p *person-fn*))
(let [ser-p (restore *person-fn*)]
(show ser-p))
{:name name :age age})
(defn show [p]
(println (format "Name=%s Age=%d" (:name p) (:age p))))
(defn save [p filename]
(with-out-writer filename (pr p)))
(defn restore [filename]
(read (PushbackReader. (reader filename))))
(let [p (person "Ken" 38)]
(show p)
(save p *person-fn*))
(let [ser-p (restore *person-fn*)]
(show ser-p))
fantom
@Serializable
class Person
{
Str name
Int age
new make(|This| f) { f(this) }
}
person := Person() { name="Tom Bones"; age=23 }
File(`tommy.dump`).out.writeObj(person).close
Person tom := File(`tommy.dump`).in.readObj
class Person
{
Str name
Int age
new make(|This| f) { f(this) }
}
person := Person() { name="Tom Bones"; age=23 }
File(`tommy.dump`).out.writeObj(person).close
Person tom := File(`tommy.dump`).in.readObj
Check your language appears on the langref.org site
Your language name should appear within the HTML found at the http:
//langreg.org main page.
php
if (preg_match("/PHP/i", file_get_contents("http://langref.org/"))) {
echo "PHP appears on langref.org";
} else {
echo "PHP doesn't appear on langref.org";
}
echo "PHP appears on langref.org";
} else {
echo "PHP doesn't appear on langref.org";
}
clojure
(def *url* "http://langref.org/")
(def *lang* "clojure")
(with-open [ stream (.openStream (URL. *url*)) ]
(let [ body (str (line-seq (BufferedReader. (InputStreamReader. stream)))) ]
(str "Language " *lang* " does "
(if-not (re-matches (re-pattern (str ".*" *url* *lang* ".*")) body) "not ")
"exist")))
(def *lang* "clojure")
(with-open [ stream (.openStream (URL. *url*)) ]
(let [ body (str (line-seq (BufferedReader. (InputStreamReader. stream)))) ]
(str "Language " *lang* " does "
(if-not (re-matches (re-pattern (str ".*" *url* *lang* ".*")) body) "not ")
"exist")))
fantom
language := "Fantom"
url := `http://langref.org/`
response := WebClient(url).getStr
if (Regex.fromStr("\\b$language.lower\\b").matcher(response).find)
echo("Language $language appears at ${url}.")
url := `http://langref.org/`
response := WebClient(url).getStr
if (Regex.fromStr("\\b$language.lower\\b").matcher(response).find)
echo("Language $language appears at ${url}.")
Send an email
Use library functions, classes or objects to create a short email addressed to your own email address. The subject should be,
"Greetings from langref.org", and the user should be prompted for the message body, and whether to cancel or proceed with sending the email.
php
/****
* For some (security)reason I couldn't
* submit this without adding a space to
* the functionnames. Please remove it :)
* in this case, only "f write" and "f gets"
****/
$to = "mail@domain.tld";
f write(STDOUT, "Mail: ".$to."\n");
$subject = "Greetings from langref.org";
f write(STDOUT, "Subject: ".$subject."\n");
f write(STDOUT, "Please type the body. Use \\n for newlines: \n");
$body = trim(f gets(STDIN)); // we get input
if ($body == "") { // if empty input
$body = "Hi! How are you?";
f write(STDOUT, "Using standard body: ".$body."\n");
}
f write(STDOUT, "Would you like to send the mail? [y/n]: ");
if (trim(f gets(STDIN)) == "y") {
if (mail($to, $subject, $body)) {
f write(STDOUT, "Success\n");
} else { // fallback
f write(STDOUT, "Failed to mail\n");
}
} else { // fallback
f write(STDOUT, "I'm sorry :(\n");
}
/* This is a version without any prompt – use it for a website */
$to = "mail@domain.tld";
$subject = "Greetings from langref.org";
$body = "Hi,\n\nHow are you?";
$headers = "From: sender@domain.tld\n"; // you can comment this out and delete it from below
if (mail($to, $subject, $body, $headers)) {
echo "Success";
}
$to = "mail@domain.tld";
$subject = "Greetings from langref.org";
$body = "Hi,\n\nHow are you?";
$headers = "From: sender@domain.tld\n"; // you can comment this out and delete it from below
if (mail($to, $subject, $body, $headers)) {
echo "Success";
}
/****
* For some (security)reason I couldn't
* submit this without adding a space to
* the functionnames. Please remove it :)
* in this case, only "f write" and "f gets"
****/
$to = "mail@domain.tld";
f write(STDOUT, "Mail: ".$to."\n");
$subject = "Greetings from langref.org";
f write(STDOUT, "Subject: ".$subject."\n");
f write(STDOUT, "Please type the body. Use \\n for newlines: \n");
$body = trim(f gets(STDIN)); // we get input
if ($body == "") { // if empty input
$body = "Hi! How are you?";
f write(STDOUT, "Using standard body: ".$body."\n");
}
f write(STDOUT, "Would you like to send the mail? [y/n]: ");
if (trim(f gets(STDIN)) == "y") {
if (mail($to, $subject, $body)) {
f write(STDOUT, "Success\n");
} else { // fallback
f write(STDOUT, "Failed to mail\n");
}
} else { // fallback
f write(STDOUT, "I'm sorry :(\n");
}
fantom
// read message body
echo("Enter message body. End the message with '.' character on a separate line:")
in := Env.cur.in
buf := StrBuf()
line := in.readLine;
while (line != null)
{
if (line.trim == ".")
break;
buf.add(line)
line = in.readLine
}
// construct email
email := Email
{
to = [ "someone@somewhere" ]
from = "me@mydomain"
subject = "Greetings from langref.org"
body = TextPart { text = buf.toStr }
}
mailClient := SmtpClient
{
host = "smtp.somewhere.net"
username = "me"
password = "my password"
log.level = LogLevel.debug
}
// send or abort
echo("Send email '$email.subject' to $email.to?: ");
line = in.readLine
echo("response=$line")
if (line?.trim.compareIgnoreCase("y") == 0)
mailClient.send(email)
else
echo("Aborted!")
echo("Enter message body. End the message with '.' character on a separate line:")
in := Env.cur.in
buf := StrBuf()
line := in.readLine;
while (line != null)
{
if (line.trim == ".")
break;
buf.add(line)
line = in.readLine
}
// construct email
email := Email
{
to = [ "someone@somewhere" ]
from = "me@mydomain"
subject = "Greetings from langref.org"
body = TextPart { text = buf.toStr }
}
mailClient := SmtpClient
{
host = "smtp.somewhere.net"
username = "me"
password = "my password"
log.level = LogLevel.debug
}
// send or abort
echo("Send email '$email.subject' to $email.to?: ");
line = in.readLine
echo("response=$line")
if (line?.trim.compareIgnoreCase("y") == 0)
mailClient.send(email)
else
echo("Aborted!")
Process an XML document
Given the XML Document:
<shopping>
<item name=
<item name=
</shopping>
Print out the total cost of the items, e.g. $14.50
<shopping>
<item name=
"bread" quantity="3" price="2.50"/>
<item name=
"milk" quantity="2" price="3.50"/>
</shopping>
Print out the total cost of the items, e.g. $14.50
php
$xmlfile = simplexml_load_file('shop.xml');
$x = 0;
foreach ($xmlfile as $xml) {
// we have to declare that it's a float
$x = $x + ($xml['quantity'] * (float)$xml['price']);
}
echo $x;
$x = 0;
foreach ($xmlfile as $xml) {
// we have to declare that it's a float
$x = $x + ($xml['quantity'] * (float)$xml['price']);
}
echo $x;
$filename = "shop.xml";
if (($fp = fopen($filename, "r"))) {
while ($data = fread($fp, 4096)) {
$data = eregi_replace(">"."[[:space:]]+"."< ",">< ", $data);
if (!xml_parse($xmlparser, $data, feof($fp))) {
$reason = xml_error_string(xml_get_error_code($xmlparser));
$reason .= xml_get_current_line_number($xmlparser);
die($reason);
}
}
xml_parser_free($xmlparser);
echo $total; // Echo the total
}
if (($fp = fopen($filename, "r"))) {
while ($data = fread($fp, 4096)) {
$data = eregi_replace(">"."[[:space:]]+"."< ",">< ", $data);
if (!xml_parse($xmlparser, $data, feof($fp))) {
$reason = xml_error_string(xml_get_error_code($xmlparser));
$reason .= xml_get_current_line_number($xmlparser);
die($reason);
}
}
xml_parser_free($xmlparser);
echo $total; // Echo the total
}
clojure
(println (format "Total cost of items are $%#.2f"
(->> (xml-seq (parse *xml-input-stream*))
(filter #(= :item (:tag %))) ; Remove all but the item tags
(map :attrs) ; Keep the attributes
(map (fn [e] (str "(* " (:quantity e) " " (:price e) ")"))) ; Get the total price as a sexp
(map read-string) ; "(* quantity price)" -> (* quantity price)
(map eval) ; (* quantity price) -> quantity*price
(apply +)))) ; Sum all elements
(->> (xml-seq (parse *xml-input-stream*))
(filter #(= :item (:tag %))) ; Remove all but the item tags
(map :attrs) ; Keep the attributes
(map (fn [e] (str "(* " (:quantity e) " " (:price e) ")"))) ; Get the total price as a sexp
(map read-string) ; "(* quantity price)" -> (* quantity price)
(map eval) ; (* quantity price) -> quantity*price
(apply +)))) ; Sum all elements
fantom
sum := 0.0
root := XParser(File(`shop.xml`).in).parseDoc.root
if (root.name == "shopping")
{
root.elems.each
{
if (it.name == "item")
{
quantity := Int.fromStr(it.get("quantity"))
price := Decimal.fromStr(it.get("price"))
sum += quantity * price;
}
}
}
echo("\$$sum")
root := XParser(File(`shop.xml`).in).parseDoc.root
if (root.name == "shopping")
{
root.elems.each
{
if (it.name == "item")
{
quantity := Int.fromStr(it.get("quantity"))
price := Decimal.fromStr(it.get("price"))
sum += quantity * price;
}
}
}
echo("\$$sum")
create some XML programmatically
Given the following CSV:
bread,3,2.50
milk,2,3.50
Produce the equivalent information in XML, e.g.:
<shopping>
<item name=
<item name=
</shopping>
bread,3,2.50
milk,2,3.50
Produce the equivalent information in XML, e.g.:
<shopping>
<item name=
"bread" quantity="3" price="2.50" />
<item name=
"milk" quantity="2" price="3.50" />
</shopping>
php
$xmllines = split("\n", $cvs);
foreach ($xmllines as $l) {
$xml[] = split(",", $l);
}
echo "<shopping>\n";
foreach ($xml as $x) {
echo "\t<item name=\"".$x[0]."\" quantity=\"".$x[1]."\" price=\"".$x[2]."\" />\n";
}
echo "</shopping>\n";
foreach ($xmllines as $l) {
$xml[] = split(",", $l);
}
echo "<shopping>\n";
foreach ($xml as $x) {
echo "\t<item name=\"".$x[0]."\" quantity=\"".$x[1]."\" price=\"".$x[2]."\" />\n";
}
echo "</shopping>\n";
clojure
(defn list->xml-item [lst]
(let [[name quantity price] (map str lst)]
{:tag :item
:attrs {:name name
:quantity quantity
:price price}}))
(defn cvs->xml [r]
(->> (map #(read-string (str "(" % ")")) (line-seq r))
(map list->xml-item)
(assoc {:tag :shopping} :content)
(emit)
(with-out-str)))
(println (cvs->xml *cvs-reader*))
(let [[name quantity price] (map str lst)]
{:tag :item
:attrs {:name name
:quantity quantity
:price price}}))
(defn cvs->xml [r]
(->> (map #(read-string (str "(" % ")")) (line-seq r))
(map list->xml-item)
(assoc {:tag :shopping} :content)
(emit)
(with-out-str)))
(println (cvs->xml *cvs-reader*))
fantom
sum := 0.0
rows := CsvInStream(File(`shop.csv`).in).readAllRows
doc := XDoc()
doc.root = XElem("shopping")
{
root := it
rows.each |Str[] row|
{
root.add(XElem("item")
{
XAttr("name", row[0]),
XAttr("quantity", row[1]),
XAttr("price", row[2])
})
}
}
os := File(`shop.xml`).out
doc.write(os)
os.close
rows := CsvInStream(File(`shop.csv`).in).readAllRows
doc := XDoc()
doc.root = XElem("shopping")
{
root := it
rows.each |Str[] row|
{
root.add(XElem("item")
{
XAttr("name", row[0]),
XAttr("quantity", row[1]),
XAttr("price", row[2])
})
}
}
os := File(`shop.xml`).out
doc.write(os)
os.close
Find all Pythagorean triangles with length or height less than or equal to 20
Pythagorean triangles are right angle triangles whose sides comply with the following equation:
a * a + b * b = c * c
where c represents the length of the hypotenuse, and a and b represent the lengths of the other two sides. Find all such triangles where a, b and c are non-zero integers with a and b less than or equal to 20. Sort your results by the size of the hypotenuse. The expected answer is:
a * a + b * b = c * c
where c represents the length of the hypotenuse, and a and b represent the lengths of the other two sides. Find all such triangles where a, b and c are non-zero integers with a and b less than or equal to 20. Sort your results by the size of the hypotenuse. The expected answer is:
[3, 4, 5]
[6, 8, 10]
[5, 12, 13]
[9, 12, 15]
[8, 15, 17]
[12, 16, 20]
[15, 20, 25]
php
for ($x = 1; $x <= 20; $x++) {
for ($y = $x; $y <= 20; $y++) {
$z = hypot($x, $y); // or $z = sqrt($x*$x + $y*$y);
if (round($z) == $z) {
$array = array($x, $y, $z);
sort($array, SORT_NUMERIC);
$res[] = $array;
}
}
}
// calculate the total of the sides
foreach ($res as $a) {
$total[] = ($a[0] + $a[1] + $a[2]);
}
array_multisort($total, $res); // and sort them after the total
// result is in $res
for ($y = $x; $y <= 20; $y++) {
$z = hypot($x, $y); // or $z = sqrt($x*$x + $y*$y);
if (round($z) == $z) {
$array = array($x, $y, $z);
sort($array, SORT_NUMERIC);
$res[] = $array;
}
}
}
// calculate the total of the sides
foreach ($res as $a) {
$total[] = ($a[0] + $a[1] + $a[2]);
}
array_multisort($total, $res); // and sort them after the total
// result is in $res
clojure
(defn pythagorean [a b c] (= (+ (* a a) (* b b)) (* c c)))
(defn intsqrt [cc]
(. (. Math sqrt cc) intValue)
)
(defn triples [maxSize]
(filter not-empty
(for [a (range 1 20) b (range a 20)]
(let [c (intsqrt (+ (* a a) (* b b)))]
(if (pythagorean a b c)
[a b c]
()
)))))
(triples 20)
; -> ([3 4 5] [5 12 13] [6 8 10] [8 15 17] [9 12 15] [12 16 20] [15 20 25])
(defn sortByHypotenuse [triples]
(sort-by #(first (rest (rest %))) triples)
)
(sortByHypotenuse (triples 20))
; -> ([3 4 5] [6 8 10] [5 12 13] [9 12 15] [8 15 17] [12 16 20] [15 20 25])
(defn intsqrt [cc]
(. (. Math sqrt cc) intValue)
)
(defn triples [maxSize]
(filter not-empty
(for [a (range 1 20) b (range a 20)]
(let [c (intsqrt (+ (* a a) (* b b)))]
(if (pythagorean a b c)
[a b c]
()
)))))
(triples 20)
; -> ([3 4 5] [5 12 13] [6 8 10] [8 15 17] [9 12 15] [12 16 20] [15 20 25])
(defn sortByHypotenuse [triples]
(sort-by #(first (rest (rest %))) triples)
)
(sortByHypotenuse (triples 20))
; -> ([3 4 5] [6 8 10] [5 12 13] [9 12 15] [8 15 17] [12 16 20] [15 20 25])
(doseq [pt (sort-by #(% 2)
(for [a (range 1 21)
b (range a 21)
:let [aa+bb (+ (* a a) (* b b))
c (Math/round (Math/sqrt aa+bb))]
:when (= aa+bb (* c c))]
[a b c]))]
(println pt))
(for [a (range 1 21)
b (range a 21)
:let [aa+bb (+ (* a a) (* b b))
c (Math/round (Math/sqrt aa+bb))]
:when (= aa+bb (* c c))]
[a b c]))]
(println pt))
fantom
triangles := [,]
(1..20).each |Int a|
{
(a..20).each |Int b|
{
c := (a.pow(2) + b.pow(2)).toFloat.sqrt
if (c % c.toInt == 0.0f && !triangles.contains([b,a,c]))
triangles.add([a,b,c.toInt])
}
}
triangles.sort |Int[] x, Int[] y -> Int| { x[2]-y[2] }
echo(triangles)
(1..20).each |Int a|
{
(a..20).each |Int b|
{
c := (a.pow(2) + b.pow(2)).toFloat.sqrt
if (c % c.toInt == 0.0f && !triangles.contains([b,a,c]))
triangles.add([a,b,c.toInt])
}
}
triangles.sort |Int[] x, Int[] y -> Int| { x[2]-y[2] }
echo(triangles)
Greatest Common Divisor
Find the largest positive integer that divides two given numbers without a remainder. For example, the GCD of 8 and 12 is 4.
clojure
(defn gcd [a b]
(if (zero? b)
a
(recur b (mod b a))))
(if (zero? b)
a
(recur b (mod b a))))
fantom
gcd := |Int a, Int b -> Int| {
pair := [a, b].sort
while (pair.first != 0)
pair.set(1, pair.last % pair.first).swap(0, 1)
return pair.last
}
echo(gcd(12, 8)) // a>b, result == 4
echo(gcd(1029, 1071)) // a<b, result == 21
pair := [a, b].sort
while (pair.first != 0)
pair.set(1, pair.last % pair.first).swap(0, 1)
return pair.last
}
echo(gcd(12, 8)) // a>b, result == 4
echo(gcd(1029, 1071)) // a<b, result == 21
produces a copy of its own source code
In computing, a quine is a computer program which produces a copy of its own source code as its only output.
php
// We make sure nothing else is outputted on the screen
ob_end_clean(); // Clean everything
die(highlight_file(__FILE__)); // Print and die
ob_end_clean(); // Clean everything
die(highlight_file(__FILE__)); // Print and die
clojure
(def s"(def s%s)(printf s(pr-str s))")(printf s(pr-str s))
fantom
class Q
{
static Void main()
{
r := "class Q\n{\n static Void main()\n {\n r := "
s := "\n s := \n echo (r+r.toCode+s[0..9]+s.toCode+s[10..-1])\n }\n}"
echo (r+r.toCode+s[0..9]+s.toCode+s[10..-1])
}
}
{
static Void main()
{
r := "class Q\n{\n static Void main()\n {\n r := "
s := "\n s := \n echo (r+r.toCode+s[0..9]+s.toCode+s[10..-1])\n }\n}"
echo (r+r.toCode+s[0..9]+s.toCode+s[10..-1])
}
}
class Q{static Void main(){s:="class Q{static Void main(){s:=;c:=34.toChar;echo(s[0..<30]+c+s+c+s[30..-1]);}}";c:=34.toChar;echo(s[0..<30]+c+s+c+s[30..-1]);}}
Subdivide A Problem To A Pool Of Workers (No Shared Data)
Take a hard to compute problem and split it up between multiple worker threads. In your solution, try to fully utilize available cores or processors. (I'm looking at you, Python!)
Note: In this question, there should be no need for shared state between worker threads while the problem is being solved. Only after every thread completes computation are the answers recombined into a single output.
Example:
-Input-
(In python syntax)
In other words, a list of random strings.
-Output-
(In python syntax)
In other words, all possible permutations of each input string are computed.
Note: In this question, there should be no need for shared state between worker threads while the problem is being solved. Only after every thread completes computation are the answers recombined into a single output.
Example:
-Input-
(In python syntax)
["ab", "we", "tfe", "aoj"]
In other words, a list of random strings.
-Output-
(In python syntax)
[ ["ab", "ba", "aa", "bb", "a", "b"], ["we", "ew", "ww", "ee", "w", "e"], ...
In other words, all possible permutations of each input string are computed.
clojure
(defn perm-chars [l]
"Returns a list of all possible permutations of strings with the
same size as the input string. This function will return duplicates
if the same character occurs multiple time in the string.
Ex: ab -> (aa ab ba ab)"
(if (string? l)
(recur (repeat (count l) l))
(let [s (first l)
r (rest l)]
(if (empty? r)
(map identity s)
(->> s
(map (fn [c] (map #(str c %) (perm-chars r))))
(flatten))))))
(defn perm-sz [s]
"Returns a list of all possible permutations of the input
string. May return duplicats.
Ex: ab -> (aa ab ba bb a b a b)"
(if-not (empty? s)
(let [r (perm-chars s)]
(if (= (count s) 1)
r
(->> r
(map #(perm-sz (apply str (rest %))))
(flatten)
(lazy-cat r))))))
(defn perm [s]
"Returns a list of all possible permutations of the input
string. The list of string is sorted and does not contain
duplicates.
Ex: ab -> (a aa ab b ba bb)"
(->> (reduce (fn [s e] (conj s e)) #{} (perm-sz s))
(map str)
(sort)))
(println (pmap perm ["ab" "we" "tfe" "aoj"]))
"Returns a list of all possible permutations of strings with the
same size as the input string. This function will return duplicates
if the same character occurs multiple time in the string.
Ex: ab -> (aa ab ba ab)"
(if (string? l)
(recur (repeat (count l) l))
(let [s (first l)
r (rest l)]
(if (empty? r)
(map identity s)
(->> s
(map (fn [c] (map #(str c %) (perm-chars r))))
(flatten))))))
(defn perm-sz [s]
"Returns a list of all possible permutations of the input
string. May return duplicats.
Ex: ab -> (aa ab ba bb a b a b)"
(if-not (empty? s)
(let [r (perm-chars s)]
(if (= (count s) 1)
r
(->> r
(map #(perm-sz (apply str (rest %))))
(flatten)
(lazy-cat r))))))
(defn perm [s]
"Returns a list of all possible permutations of the input
string. The list of string is sorted and does not contain
duplicates.
Ex: ab -> (a aa ab b ba bb)"
(->> (reduce (fn [s e] (conj s e)) #{} (perm-sz s))
(map str)
(sort)))
(println (pmap perm ["ab" "we" "tfe" "aoj"]))
(require 'cojure.contrib.combinatorics)
(pmap (fn [str]
(apply concat (map #(selections str (inc %))
(range (count str)))))
["ab", "we", "tfe", "aoj"])
(pmap (fn [str]
(apply concat (map #(selections str (inc %))
(range (count str)))))
["ab", "we", "tfe", "aoj"])
fantom
using concurrent
// as per Java answer, doesn't duplicate chars from input string, i.e. no 'aa'
const class PermGen : Actor
{
new make(ActorPool pool) : super(pool) {}
Void permutations(Str prefix, Str w, Str[] pset)
{
n := w.size
if (n == 0)
{
if (!pset.contains(prefix))
pset.add(prefix)
return
}
n.times { permutations(prefix + w[it..it], w[0..<it] + w[it+1..<n], pset) }
}
override Obj? receive(Obj? msg)
{
Str word := msg
wordSubPerm := Str[,]
for (Int i := 0; i < word.size; i++)
for (Int j := i; j < word.size; j++)
permutations("", word[i..j], wordSubPerm)
return wordSubPerm
}
}
class SolutionXX
{
static Void main()
{
pool := ActorPool() { maxThreads = 8 }
futures := Future[,]
["ab", "we", "tfe", "aoj"].each { futures.add(PermGen(pool).send(it)) }
futures.each { echo(it.get) }
}
}
// as per Java answer, doesn't duplicate chars from input string, i.e. no 'aa'
const class PermGen : Actor
{
new make(ActorPool pool) : super(pool) {}
Void permutations(Str prefix, Str w, Str[] pset)
{
n := w.size
if (n == 0)
{
if (!pset.contains(prefix))
pset.add(prefix)
return
}
n.times { permutations(prefix + w[it..it], w[0..<it] + w[it+1..<n], pset) }
}
override Obj? receive(Obj? msg)
{
Str word := msg
wordSubPerm := Str[,]
for (Int i := 0; i < word.size; i++)
for (Int j := i; j < word.size; j++)
permutations("", word[i..j], wordSubPerm)
return wordSubPerm
}
}
class SolutionXX
{
static Void main()
{
pool := ActorPool() { maxThreads = 8 }
futures := Future[,]
["ab", "we", "tfe", "aoj"].each { futures.add(PermGen(pool).send(it)) }
futures.each { echo(it.get) }
}
}
Subdivide A Problem To A Pool Of Workers (Shared Data)
Take a hard to compute problem and split it up between multiple worker threads. In your solution, try to fully utilize available cores or processors. (I'm looking at you, Python!)
Note: In this question, there should be a need for shared state between worker threads while the problem is being solved.
Example:
-Conway Game of Life-
From Wikipedia:
The universe of the Game of Life is an infinite two-dimensional orthogonal grid of square cells, each of which is in one of two possible states, live or dead. Every cell interacts with its eight neighbors, which are the cells that are directly horizontally, vertically, or diagonally adjacent. At each step in time, the following transitions occur:
1. Any live cell with fewer than two live neighbours dies, as if caused by underpopulation.
2. Any live cell with more than three live neighbours dies, as if by overcrowding.
3. Any live cell with two or three live neighbours lives on to the next generation.
4. Any dead cell with exactly three live neighbours becomes a live cell.
The initial pattern constitutes the seed of the system. The first generation is created by applying the above rules simultaneously to every cell in the seed—births and deaths happen simultaneously, and the discrete moment at which this happens is sometimes called a tick (in other words, each generation is a pure function of the one before). The rules continue to be applied repeatedly to create further generations.
--However, for our purposes, we will assign a size to the game
Notice that in this problem, at each step or
Note: In this question, there should be a need for shared state between worker threads while the problem is being solved.
Example:
-Conway Game of Life-
From Wikipedia:
The universe of the Game of Life is an infinite two-dimensional orthogonal grid of square cells, each of which is in one of two possible states, live or dead. Every cell interacts with its eight neighbors, which are the cells that are directly horizontally, vertically, or diagonally adjacent. At each step in time, the following transitions occur:
1. Any live cell with fewer than two live neighbours dies, as if caused by underpopulation.
2. Any live cell with more than three live neighbours dies, as if by overcrowding.
3. Any live cell with two or three live neighbours lives on to the next generation.
4. Any dead cell with exactly three live neighbours becomes a live cell.
The initial pattern constitutes the seed of the system. The first generation is created by applying the above rules simultaneously to every cell in the seed—births and deaths happen simultaneously, and the discrete moment at which this happens is sometimes called a tick (in other words, each generation is a pure function of the one before). The rules continue to be applied repeatedly to create further generations.
--However, for our purposes, we will assign a size to the game
"board": 2^k * 2^k . That is, the board should be easy to subdivide.
Notice that in this problem, at each step or
"tick", each thread/process will need to share data with its neighborhood.
clojure
; This is a "glider"
(def *start*
[".O......"
"..O....."
"OOO....."
"........"
"........"
"........"
"........"])
(def *width* (count (first *start*)))
(def *height* (count *start*))
(def *live* \O)
(def *dead* \.)
(def *n-generations-to-show* 3)
(defn cell-at
([b coord]
(cell-at b coord {:col 0 :row 0}))
([b coord offset]
(let [x (mod (+ (:col coord) (:col offset)) *width*)
y (mod (+ (:row coord) (:row offset)) *height*)]
(nth (nth b y) x))))
(defn neighbor-count [b coord]
(->> (for [x (range -1 2) y (range -1 2)] {:col x :row y})
(filter #(not (= {:col 0 :row 0} %)))
(map (partial cell-at b coord))
(reduce (fn [sum n] (+ sum (if (= *live* n) 1 0))) 0)))
(defn next-generation-cell [b coord]
(let [nc (neighbor-count b coord)]
(cond (< nc 2) *dead*
(> nc 3) *dead*
(= nc 3) *live*
true (cell-at b coord))))
(defn next-generation-row [b row]
(->> (range *width*)
(map #(next-generation-cell b {:col % :row row}))
(apply str)))
(defn next-generation [b]
(->> (range *height*)
(pmap #(next-generation-row b %))))
(defn generation-seq [b]
(let [ng (next-generation b)]
(lazy-seq (cons ng (generation-seq ng)))))
(doseq [g (take *n-generations-to-show* (generation-seq *start*))]
(doseq [l g]
(println l))
(println))
(shutdown-agents)
; This version calculates each separate line on a separate thread (pmap in next-generation)
(def *start*
[".O......"
"..O....."
"OOO....."
"........"
"........"
"........"
"........"])
(def *width* (count (first *start*)))
(def *height* (count *start*))
(def *live* \O)
(def *dead* \.)
(def *n-generations-to-show* 3)
(defn cell-at
([b coord]
(cell-at b coord {:col 0 :row 0}))
([b coord offset]
(let [x (mod (+ (:col coord) (:col offset)) *width*)
y (mod (+ (:row coord) (:row offset)) *height*)]
(nth (nth b y) x))))
(defn neighbor-count [b coord]
(->> (for [x (range -1 2) y (range -1 2)] {:col x :row y})
(filter #(not (= {:col 0 :row 0} %)))
(map (partial cell-at b coord))
(reduce (fn [sum n] (+ sum (if (= *live* n) 1 0))) 0)))
(defn next-generation-cell [b coord]
(let [nc (neighbor-count b coord)]
(cond (< nc 2) *dead*
(> nc 3) *dead*
(= nc 3) *live*
true (cell-at b coord))))
(defn next-generation-row [b row]
(->> (range *width*)
(map #(next-generation-cell b {:col % :row row}))
(apply str)))
(defn next-generation [b]
(->> (range *height*)
(pmap #(next-generation-row b %))))
(defn generation-seq [b]
(let [ng (next-generation b)]
(lazy-seq (cons ng (generation-seq ng)))))
(doseq [g (take *n-generations-to-show* (generation-seq *start*))]
(doseq [l g]
(println l))
(println))
(shutdown-agents)
; This version calculates each separate line on a separate thread (pmap in next-generation)
Create a multithreaded "Hello World"
Create a program which outputs the string
Example:
-Output-
Thread one says Hello World!
Thread two says Hello World!
Thread four says Hello World!
Thread three says Hello World!
-Notice that the threads can print in any order.
"Hello World" to the console, multiple times, using separate threads or processes.
Example:
-Output-
Thread one says Hello World!
Thread two says Hello World!
Thread four says Hello World!
Thread three says Hello World!
-Notice that the threads can print in any order.
php
/*
The commented lines below can be used to verify new process are in use
*/
$text=array("one","two","three","four");
for ($i = 0; $i < 4; ++$i) {
$pid = pcntl_fork();
//$mypid=getmypid();
if (!$pid) {
//echo("Thread ".$text[$i]." says Hello World!(".$mypid.")\n");
echo("Thread ".$text[$i]." says Hello World!\n");
exit($i);
}
}
The commented lines below can be used to verify new process are in use
*/
$text=array("one","two","three","four");
for ($i = 0; $i < 4; ++$i) {
$pid = pcntl_fork();
//$mypid=getmypid();
if (!$pid) {
//echo("Thread ".$text[$i]." says Hello World!(".$mypid.")\n");
echo("Thread ".$text[$i]." says Hello World!\n");
exit($i);
}
}
clojure
(doseq [msg ["one" "two" "three" "four"]]
(future (println "Thread" msg "says Hello World!")))
(future (println "Thread" msg "says Hello World!")))
(dorun (pmap #(println (str "Thread " % " says Hello World!")) '("one" "two" "three" "four")))
(dorun (map (fn [n] (.start (Thread. #(println (str "Thread " n " says Hello World!")))))
'("one" "two" "three" "four")))
'("one" "two" "three" "four")))
fantom
pool := ActorPool()
["one", "two", "three", "four"].each
{
a := Actor(pool) |Str name| { echo("Thread $name says Hello World!") }
a.send(it)
}
["one", "two", "three", "four"].each
{
a := Actor(pool) |Str name| { echo("Thread $name says Hello World!") }
a.send(it)
}
Create read/write lock on a shared resource.
Create multiple threads or processes who are either readers or writers. There should be more readers then writers.
(From Wikipedia):
Multiple readers can read the data in parallel but an exclusive lock is needed while writing the data. When a writer is writing the data, readers will be blocked until the writer is finished writing.
Example:
-Output-
Thread one says that the value is 8.
Thread three says that the value is 8.
Thread two is taking the lock.
Thread four tried to read the value, but could not.
Thread five tried to write to the value, but could not.
Thread two is changing the value to 9.
Thread two is releasing the lock.
Thread four says that the value is 9.
...
--Notice that when a needed resource is locked, a thread can set a timer and try again in the future, or wait to be notified that the resource is no longer locked.
(From Wikipedia):
Multiple readers can read the data in parallel but an exclusive lock is needed while writing the data. When a writer is writing the data, readers will be blocked until the writer is finished writing.
Example:
-Output-
Thread one says that the value is 8.
Thread three says that the value is 8.
Thread two is taking the lock.
Thread four tried to read the value, but could not.
Thread five tried to write to the value, but could not.
Thread two is changing the value to 9.
Thread two is releasing the lock.
Thread four says that the value is 9.
...
--Notice that when a needed resource is locked, a thread can set a timer and try again in the future, or wait to be notified that the resource is no longer locked.
clojure
; NOTE! Using explicit locking is NOT the Clojure way. It was done
; this way in order to comply exactly with the problem
; specification. Sharing data in Clojure would normally be done by
; using "atom", "agent" or "ref" depending on situation. None of those
; methods would ever result in the reader not being able to read (as
; required by the problem) since reading is wait-free in clojure.
(def *readers* (map #(agent %) '("one" "two" "three")))
(def *writers* (map #(agent %) '("four" "five")))
(def *mutex* (agent :unlocked))
(def *value* 0)
; mutex implementation
(defn lock [state who success-fn fail-fn]
(send who (if (= state :locked) fail-fn success-fn))
:locked)
(defn unlock [mutex]
:unlocked)
; Must be invoked with send-off since this handler blocks
(defn rand-sleep [state next-fn]
(Thread/sleep (rand-int 5))
(send *agent* next-fn)
state)
; Reader functions
(declare try-read)
(defn reader-got-lock [name]
(println (format "Thread %s says that the value is %d." name *value*))
(send *mutex* unlock)
(send-off *agent* rand-sleep try-read)
name)
(defn reader-did-not-get-lock [name]
(println (format "Thread %s tried to read the value, but could not." name))
(send-off *agent* rand-sleep try-read)
name)
(defn try-read [name]
(send *mutex* lock *agent* reader-got-lock reader-did-not-get-lock)
name)
; Writer functions
(declare try-write)
(defn writer-got-lock [name]
(println (format "Thread %s is taking the lock." name))
(def *value* (rand-int 10))
(println (format "Thread %s is changing the value to %d." name *value*))
(send *mutex* unlock)
(println (format "Thread %s is relasing the lock." name))
(send-off *agent* rand-sleep try-write)
name)
(defn writer-did-not-get-lock [name]
(println (format "Thread %s tried to write the value, but could not." name))
(send-off *agent* rand-sleep try-write)
name)
(defn try-write [name]
(send *mutex* lock *agent* writer-got-lock writer-did-not-get-lock)
name)
(dorun (map #(send % try-write) *writers*))
(dorun (map #(send % try-read) *readers*))
; this way in order to comply exactly with the problem
; specification. Sharing data in Clojure would normally be done by
; using "atom", "agent" or "ref" depending on situation. None of those
; methods would ever result in the reader not being able to read (as
; required by the problem) since reading is wait-free in clojure.
(def *readers* (map #(agent %) '("one" "two" "three")))
(def *writers* (map #(agent %) '("four" "five")))
(def *mutex* (agent :unlocked))
(def *value* 0)
; mutex implementation
(defn lock [state who success-fn fail-fn]
(send who (if (= state :locked) fail-fn success-fn))
:locked)
(defn unlock [mutex]
:unlocked)
; Must be invoked with send-off since this handler blocks
(defn rand-sleep [state next-fn]
(Thread/sleep (rand-int 5))
(send *agent* next-fn)
state)
; Reader functions
(declare try-read)
(defn reader-got-lock [name]
(println (format "Thread %s says that the value is %d." name *value*))
(send *mutex* unlock)
(send-off *agent* rand-sleep try-read)
name)
(defn reader-did-not-get-lock [name]
(println (format "Thread %s tried to read the value, but could not." name))
(send-off *agent* rand-sleep try-read)
name)
(defn try-read [name]
(send *mutex* lock *agent* reader-got-lock reader-did-not-get-lock)
name)
; Writer functions
(declare try-write)
(defn writer-got-lock [name]
(println (format "Thread %s is taking the lock." name))
(def *value* (rand-int 10))
(println (format "Thread %s is changing the value to %d." name *value*))
(send *mutex* unlock)
(println (format "Thread %s is relasing the lock." name))
(send-off *agent* rand-sleep try-write)
name)
(defn writer-did-not-get-lock [name]
(println (format "Thread %s tried to write the value, but could not." name))
(send-off *agent* rand-sleep try-write)
name)
(defn try-write [name]
(send *mutex* lock *agent* writer-got-lock writer-did-not-get-lock)
name)
(dorun (map #(send % try-write) *writers*))
(dorun (map #(send % try-read) *readers*))
Separate user interaction and computation.
Allow your program to accept user interaction while conducting a long running computation.
Example:
Hello user! Please input a string to permute: (input thread)
abcdef
Passing on abcdef... (input thread)
Please input another string to permute: (input thread)
lol
Passing on lol... (input thread)
Done Work On abcdef! (worker thread)
Please input another string to permute: (input thread)
EXIT
Quitting, I
--Notice, that this could be accomplished on the command line or within a GUI. The point is that computation and user interaction should take place on separate threads of control.
Example:
Hello user! Please input a string to permute: (input thread)
abcdef
Passing on abcdef... (input thread)
Please input another string to permute: (input thread)
lol
Passing on lol... (input thread)
Done Work On abcdef! (worker thread)
["abcdef", "abcefd", ... ] (worker thread)
Please input another string to permute: (input thread)
EXIT
Quitting, I
'll let my worker thread know... (input thread)
We're quitting! Alright! (worker thread)
--Notice, that this could be accomplished on the command line or within a GUI. The point is that computation and user interaction should take place on separate threads of control.
clojure
(defn background-computation [_ s]
(let [res (permutations s)]
(println (format "Done Work On %s!" s))
(println res)))
(defn shutdown-app [_]
(println "We're quitting! Alright!")
(shutdown-agents))
(println "Hello user! Please input a string to permute: ")
(let [worker-agent (agent nil)]
(loop [input (str (read))]
(if (= input "EXIT")
(do (println "Quitting, I'll let my worker thread know...")
(send worker-agent shutdown-app))
(do (println (format "Passing on %s..." input))
(send worker-agent background-computation input)
(println "Please input another string to permute: ")
(recur (str (read)))))))
(let [res (permutations s)]
(println (format "Done Work On %s!" s))
(println res)))
(defn shutdown-app [_]
(println "We're quitting! Alright!")
(shutdown-agents))
(println "Hello user! Please input a string to permute: ")
(let [worker-agent (agent nil)]
(loop [input (str (read))]
(if (= input "EXIT")
(do (println "Quitting, I'll let my worker thread know...")
(send worker-agent shutdown-app))
(do (println (format "Passing on %s..." input))
(send worker-agent background-computation input)
(println "Please input another string to permute: ")
(recur (str (read)))))))
fantom
using concurrent
class Main
{
static Void main()
{
worker := Actor(ActorPool()) |Str s|
{
result := permute(s.chars).map { Str.fromChars(it) }
echo("Done Work On $s!")
echo(result)
}
Env.cur.out.writeChars("Hello, user! Please input a string to permute: ").flush
Env.cur.in.eachLine |line| {
echo("Passing on $line ...")
worker.send(line)
Env.cur.out.writeChars("Please input another string to permute: ").flush
}
}
static Obj[][] permute(Obj[] list, Obj[] prefix := [,])
{
list.isEmpty ?
[prefix] :
list.reduce([,]) |Obj[] r, Obj item, Int i -> Obj[]| {
r.addAll(permute(list.dup { removeAt(i) }, prefix.dup.add(item)))
}
}
}
class Main
{
static Void main()
{
worker := Actor(ActorPool()) |Str s|
{
result := permute(s.chars).map { Str.fromChars(it) }
echo("Done Work On $s!")
echo(result)
}
Env.cur.out.writeChars("Hello, user! Please input a string to permute: ").flush
Env.cur.in.eachLine |line| {
echo("Passing on $line ...")
worker.send(line)
Env.cur.out.writeChars("Please input another string to permute: ").flush
}
}
static Obj[][] permute(Obj[] list, Obj[] prefix := [,])
{
list.isEmpty ?
[prefix] :
list.reduce([,]) |Obj[] r, Obj item, Int i -> Obj[]| {
r.addAll(permute(list.dup { removeAt(i) }, prefix.dup.add(item)))
}
}
}
Put a internationalizate of HelloWorld program
Set locale to
In pseudocode:
Void main ()
"es" (spanish) and provide a program that changes outputs ("Helloworld") depending of locale.
In pseudocode:
Void main ()
{
Locale.set("es")
print.translate("Helloworld, Locale.get)
}
fantom
Locale("es).use
class Foo { Void main() { echo(#Foo.pod.locale("hello world!")) } }
class Foo { Void main() { echo(#Foo.pod.locale("hello world!")) } }
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