Solved 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");
erlang
io:format("Hello, World!~n").
csharp
System.Console.WriteLine("Hello World!")
clojure
(println "Hello World!")
groovy
println "Hello World!"

Define a string containing special characters

Define the literal string "\#{'}${"}/"
php
$special = "\\#{'}\${\"}/";
$special = '\#{\'}${"}/';
erlang
Special = "\\#{'}\${\"}/",
csharp
string verbatim = @"\#{'}${""""}/";
string cStyle = "\\#{'}${\"\"}/";
clojure
(def special "\\#{'}${\"}/")
groovy
special = "\\#{'}\${\"}/"
special = '\\#{\'}${"}/'
special = /\#{'}${'$'}{"}\//

Define a multiline string

Define the string:
"This
Is
A
Multiline
String"
php
$multiline = <<<ML
This
Is
A
Multiline
String
ML;
$multiline = "This
Is
A
Multiline
String";
$multiline = "This\nIs\nA\nMultiline\nString";
erlang
Text = "This\nIs\nA\nMultiline\nString",
csharp
string output = "This\nIs\nA\nMultiline\nString";
string output = @"This
Is
A
Multiline
String";
clojure
(def multiline "This\nIs\nA\nMultiline\nString")
groovy
def text =
"""This
Is
A
Multiline
String"""
def text = "This\nIs\nA\nMultiline\nString"

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 + $b);
erlang
A = 3, B = 4,
io:format("~B+~B=~B~n", [A, B, (A+B)]).
csharp
int a = 3;
int b = 4;
Console.WriteLine("{0}+{1}={2}", a,b,a+b);
clojure
(format "%d + %d = %d" a b (+ a b))
groovy
println "$a+$b=${a+b}"
printf "%d+%d=%d\n", 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");
erlang
Reversed = lists:reverse("reverse me"),
Reversed = revchars("reverse me"),
csharp
var str = "reverse me";
Console.WriteLine(new String(str.Reverse().ToArray()));
clojure
(require '[clojure.contrib.str-utils2 :as str])
(str/reverse "reverse me")
(apply str (reverse "reverse me"))
groovy
reversed = "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!")));
erlang
Reversed = string:join(lists:reverse(string:tokens("This is the end, my only friend!", " ")), " "),
csharp
var str = "This is a end, my only friend!";
str = String.Join(" ", str.Split().Reverse().ToArray());
Console.WriteLine(str);
clojure
(require '[clojure.contrib.str-utils2 :as str])
(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!"))))
groovy
reversed = "This is the end, my only friend!".split().reverse().join(' ')
reversed = "This is the end, my only friend!".tokenize(' ').reverse().join(' ')
def revdelim(c, s) { StringUtils.reverseDelimited(s, c) }
revwords = this.&revdelim.curry(" " as char)
reversed = revwords("This is the end, my only friend!")
reversed = StringUtils.reverseDelimited("This is the end, my only friend!", " " as char)

Text wrapping

Wrap the string "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;
echo '> '.wordwrap(str_repeat('The quick brown fox jumps over the lazy dog. ', 10), 70,"\n> ")."\n";
erlang
TextWrap = textwrap(string:copies(Input, 10), 73 - length(Prefix)),
lists:foreach(fun (Line) -> io:format("~s~n", [string:concat(Prefix, Line)]) end, string:tokens(TextWrap, "\n")).
csharp
using System;
using System.Text;
using System.Linq; // used for Array.ToList() extension

public class TextWrapper {

/// <summary>
/// Wrap the given text to a given width.
/// </summary>
/// <param name="text">The text to be wrapped</param>
/// <param name="width">The maximum width of each line</param>
/// <param name="prefix">Begin each line with this prefix</param>
/// <returns>The wrapped text</returns>
public string Wrap(string text, int width, string prefix) {

var words = text.Split(' ').ToList();
var result = new StringBuilder(prefix);

width = width - prefix.Length;
prefix = "\n" + prefix;

int lineSize = 0;
foreach (var word in words) {
int wordLen = word.Length;

// Do we need to start a new line?
if ((lineSize + wordLen) > width) {
result.Remove(result.Length - 1, 1); // remove trailing space
lineSize = 0;
result.Append( prefix );
}

result.Append(word).Append(' ');
lineSize += wordLen + 1;
}

return result.ToString();
}

public static void Main() {
var prefix = "> ";
var sentence = "The quick brown fox jumps over the lazy dog. ";

var text = "";
for (int i = 0; i < 10; i++)
text += sentence;

// The description said lines of length 78, but
// the example was 72...
Console.WriteLine(new TextWrapper().Wrap(text, 72, prefix));
}
}
clojure
(doseq [line (re-seq #".{0,70} "
(apply str
(repeat 10 "The quick brown fox jumps over the lazy dog. ")))]
(println ">" line))
groovy
// no built-in fill, define one using brute force approach
def fill(text, width=80, prefix='') {
width = width - prefix.size()
def out = []
List words = text.replaceAll("\n", " ").split(" ")
while (words) {
def line = ''
while (words) {
if (line.size() + words[0].size() + 1 > width) break
if (line) line += ' '
line += words[0]
words = words.tail()
}
out += prefix + line
}
out.join("\n")
}
println fill('The quick brown fox jumps over the lazy dog. ' * 10, 72, '> ')
// no built-in fill, define one using lastIndexOf
def fill(text, width=80, prefix='') {
def out = ''
def remaining = text.replaceAll("\n", " ")
while (remaining) {
def next = prefix + remaining
def found = next.lastIndexOf(' ', width)
if (found == -1) remaining = ''
else {
remaining = next.substring(found + 1)
next = next[0..found]
}
out += next + '\n'
}
out
}
println fill('The quick brown fox jumps over the lazy dog. ' * 10, 72, '> ')
prefix = '> '
input = 'The quick brown fox jumps over the lazy dog. '
wrap(input * 10, 72 - prefix.size()).eachLine{ println prefix + it }

Remove leading and trailing whitespace from a string

Given the string "  hello    " return the string "hello".
php
$hello_trimmed = trim(" hello ");
erlang
Trimmed = string:strip(S),
csharp
string str = " hello ";
str = str.Trim();
Console.WriteLine(str);
clojure
(use 'clojure.contrib.str-utils2)
(trim " hello ")
(clojure.string/trim " hello ")
(.trim " hello ")
groovy
assert "hello" == " hello ".trim()

Make a string uppercase

Transform "Space Monkey" into "SPACE MONKEY"
php
echo strtoupper("Space Monkey");
erlang
io:format("~s~n", [string:to_upper("Space Monkey")]).
csharp
string output = "Space Monkey"

System.Console.WriteLine(output.ToUpper())
clojure
(.toUpperCase "Space Monkey")
groovy
println "Space Monkey".toUpperCase()

Make a string lowercase

Transform "Caps ARE overRated" into "caps are overrated"
php
echo strtolower("Caps ARE overRated");
erlang
io:format("~s~n", [string:to_lower("Caps ARE overRated")]).
csharp
string str = "Caps ARE overRated";
str = str.ToLower() ;
Console.WriteLine(str);
clojure
(.toLowerCase "Caps ARE overRated")
groovy
println "Caps ARE overRated".toLowerCase()

Capitalise the first letter of each word

Transform "man OF stEEL" into "Man Of Steel"
php
echo ucwords(strtolower("man OF stEEL"));
erlang
Caps = string:join(lists:map(fun(S) -> to_caps(S) end, string:tokens("man OF stEEL", " ")), " "),
csharp
System.Threading.Thread.CurrentThread.CurrentCulture.TextInfo.ToTitleCase("man OF stEEL".ToLowerInvariant());
clojure
(use 'clojure.contrib.str-utils2)
(join " " (map capitalize (split "man OF stEEL" #" ")))
groovy
def capitalize(s) { s[0].toUpperCase() + s[1..-1].toLowerCase() }
caps = "man OF stEEL".replaceAll(/\w+/) { w -> capitalize(w) }
caps = "man OF stEEL".replaceAll(/\w+/) { w -> StringUtils.capitalize(w.toLowerCase()) }
caps = WordUtils.capitalizeFully("man OF stEEL")

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) );
erlang
Distance = distance({point, 34, 78}, {point, 67, -45}),
io:format("~.2f~n", [Distance]).
Distance = distance(point:new(34, 78), point:new(67, -45)),
io:format("~.2f~n", [Distance]).
csharp
System.Drawing.Point p = new System.Drawing.Point(13, 14),
p1 = new System.Drawing.Point(10, 10);
double distance = Math.Sqrt(Math.Pow(p1.X - p.X, 2) + Math.Pow(p1.Y - p.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"
[[x1 y1] [x2 y2]]
(Math/sqrt
(+ (Math/pow (- x1 x2) 2)
(Math/pow (- y1 y2) 2))))

(distance [2 2] [3 3])
groovy
distance = distance(x1, y1, x2, y2)
distance = sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1))

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);
erlang
Formatted = io_lib:format("~8..0B", [42]),
io:format("~8..0B~n", [42]).
csharp
string.Format("{0,8:D8}", 42);
clojure
(defn pad
([x] (if (> 8 (.length (str x))) (pad (str 0 x)) (str x)))
)
(defn pad [x]
(format "%08d" x))
(format "%08d" 42)
groovy
formatted = new DecimalFormat('00000000').format(42)
formatted = 42.toString().padLeft(8, '0')
// to stdout
printf "%08d\n", 42
// to a string
formatted = sprintf("%08d", 42)
formatted = String.format("%08d", 42)

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);
erlang
Formatted = io_lib:format("~-6B", [1024]),
io:format("~-6B~n", [1024]).
csharp
public class NumberRightPadding {
public static void Main() {
string withStringDotFormat = string.Format("{0,-6}", 1024);
string withToStringDotPadRight = 1024.ToString().PadRight(6);
}
}
clojure
(let [s (str 1024)
l (count s)]
(str s (reduce str (repeat (- 6 l) " "))))
groovy
println 1024.toString().padRight(6)
formatted = sprintf("%-6d", 1024)

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);
erlang
Formatted = io_lib:format("~.2f", [7/8]),
io:format("~.2f~n", [7/8]).
csharp
public class FormatDecimal {
public static void Main() {
decimal result = decimal.Round( 7 / 8m, 2);
System.Console.WriteLine(result);
}
}
clojure
(format "%3.2f" (/ 7.0 8))
(* 0.01 (Math/round (* 100 (float (/ 7 8)))))
groovy
def result = 7/8
println result.round(new MathContext(2))
def result = 7/8
printf "%.2g", result
new Double(7/8).round(2)

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);
erlang
Formatted = io_lib:format("~10B", [73]),
io:format("~10B~n", [73]).
csharp
public class NumberLeftPadding {
public static void Main() {
string withStringDotFormat = string.Format("{0,10}", 73);
string withToStringDotPadLeft = 73.ToString().PadLeft(10);
}
}
clojure
(let [s (str 73)
l (count s)]
(str (reduce str (repeat (- 10 l) " ")) s ))
groovy
println 73.toString().padLeft(10)
printf "%10d\n", 73

Generate a random integer in a given range

Produce a random integer between 100 and 200 inclusive
php
$r = mt_rand(100, 200);
erlang
RandomInt = gen_rand_integer(100, 200),
csharp
System.Random r = new System.Random();
int random = r.Next(100,201);
clojure
(+ (rand-int (- 201 100)) 100)
groovy
random = new Random()
randomInt = random.nextInt(200-100+1)+100

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);
}
erlang
setRNG(RNGState),
io:format("~w~n", [lists:map(fun (_) -> gen_rand_integer(100, 200) end, lists:seq(1, 5))]),

setRNG(RNGState),
io:format("~w~n", [lists:map(fun (_) -> gen_rand_integer(100, 200) end, lists:seq(1, 5))]).
csharp
using System;

public class RepeatableRandom {
public static void Main() {
var r = new Random(12); // seed is 12

for (int i = 0; i < 5; i++)
Console.WriteLine(r.Next());

r = new Random(12);

for (int i = 0; i < 5; i++)
Console.WriteLine(r.Next());
}
}

clojure
(dotimes [_ 2]
(let [r (java.util.Random. 12345)]
(dotimes [_ 5]
(println (.nextInt r 100))))
(println))
groovy
random = new Random(12345)
orig = (1..5).collect { random.nextInt(200-100+1)+100 }
random = new Random(12345)
repeat = (1..5).collect { random.nextInt(200-100+1)+100 }
assert orig == repeat

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";
}
if(preg_match('/[A-Za-z]+/', 'Hello')>0) {
echo "ok";
}
erlang
String = "Hello", Regexp = "[A-Z][a-z]+",
is_match(String, Regexp) andalso (begin io:format("ok~n"), true end).
case re:run("Hello", "[A-Z][a-z]+") of {match, _} -> ok end.
csharp
if (Regex.IsMatch("Hello", "[A-Z][a-z]+"))
{
Console.WriteLine("ok");
}
clojure
(if (re-matches #"[A-Z][a-z]+" "Hello")
(println "ok"))
groovy
if ("Hello" =~ /[A-Z][a-z]+/) println 'ok'
if ("Hello".find(/[A-Z][a-z]+/)) println 'ok'
// with precompiled regex
def regex = ~/[A-Z][a-z]+/
if ("Hello".find(regex)) println 'ok'
// with precompiled regex
def regex = ~/[A-Z][a-z]+/
if ("Hello".matches(regex)) println 'ok'
if ("Hello".matches("[A-Z][a-z]+")) println '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];
ereg('one (.*) three', 'one two three', $regs);
echo $regs[1];
erlang
case re:run("one two three", "one (.*) three", [{capture, [1], list}]) of {match, Res} -> hd(Res) end.
csharp
using System;
using System.Text.RegularExpressions;

public class RegexBackReference {
public static void Main() {
var oneTwoThree = "one two three";
var pattern = "one (.*) three";

Match match = Regex.Match(oneTwoThree, pattern);

// group 0 is the entire match. 1 is the first backreference
Console.WriteLine(match.Groups[1]);
}
}
clojure
(if-let [groups (re-matches #"one (.*) three" "one two three")]
(println (second groups)))
groovy
matcher = ("one two three" =~ /one (.*) three/)
if (matcher) println matcher[0][1]
match = "one two three".find("one (.*) three") { it[1] }
if (match) println match

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";
erlang
% Erlang uses 'egrep'-compatible regular expressions, so shortcuts like '\d' not supported
String = "abc 123 @#$", Regexp = "[0-9]+",
is_match(String, Regexp) andalso (begin io:format("ok~n"), true end).
case re:run("abc 123 @#$", "\\d+") of {match, _} -> ok end.
csharp
if(System.Text.RegularExpressions.Regex.IsMatch("abc 123 @#$",@"\d+")){
Console.WriteLine("ok");
}
clojure
(if (re-find #"\d+" "abc 123 @#$")
(println "ok"))
groovy
if ('abc 123 @#$' =~ /\d+/) println 'ok'
if ('abc 123 @#$'.find(/\d+/)) println '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];
}
erlang
solve(S) ->
R = "\\((\\w+?)\\):(\\d+)",
{match, M} = re:run(S,R, [global, {capture, all_but_first, list}]),
[ A++N || [A, N] <- M].
csharp
using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;

public static class extensions {
public static IList<string> Map(this string me, string pattern, Func<Match, string> action){
IList<string> matches = new List<string>();
foreach (Match match in Regex.Matches(me,pattern)){
matches.Add(action(match));
}
return matches;
}
}

class Test
{
static void Main()
{
IList<string> list = "(fish):1 sausage (cow):3 tree (boat):4".Map(@"\((\w+)\):(\d+)", (m) => {return m.Groups[1].Value + m.Groups[2].Value;});
}
}
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)))
groovy
list = (text =~ /\((\w+)\):(\d+)/).collect{ it[1] + it[2] }
list = []
text.eachMatch(/\((\w+)\):(\d+)/){
list << it[1] + it[2]
}
list = []
text.eachMatch(/\((\w+)\):(\d+)/){ m, name, number ->
list << "$name$number"
}
list = (text =~ /\((\w+)\):(\d+)/).collect{ all, name, num -> "$name$num" }
list = text.findAll(regex){ _, name, num -> "$name$num" }
list = text.findAll(regex){ it[1] + it[2] }

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');
erlang
% Erlang uses 'egrep'-compatible regular expressions, so shortcuts like '\w' not supported
{ok, Replaced, _} = regexp:gsub("She sells sea shells", "se[A-Za-z0-9_]+", "X"),
re:replace("She sells sea shells", "se\\w+", "X", [global, {return, list}]).
csharp
using System.Text.RegularExpressions;

class SolutionXX
{
static void Main()
{
string text = "She sells sea shells";
string result = Regex.Replace(text, @"se\w+", "X");
}
}
clojure
(.replaceAll (re-matcher #"se\w+" "She sells sea shells") "X")
groovy
replaced = text.replaceAll(/se\w+/,"X")

Define an empty list

Assign the variable "list" to a list with no elements
php
$list = array();
erlang
List = [],
csharp
var list = new List<object>();
clojure
(list)
'()
groovy
list = []
// if a special kind of list is required
list = new LinkedList() // java style
LinkedList list = [] // statically typed
// using 'as' operator
list = [] as java.util.concurrent.CopyOnWriteArrayList

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";
<?php
$list = new SplFixedArray(5);

$list[0] = "One";
$list[1] = "Two";
$list[2] = "Three";
$list[3] = "Four";
$list[4] = "Five";
?>
erlang
List = [one, two, three, four, five],
List = ['One', 'Two', 'Three', 'Four', 'Five'],
csharp
IList<string> list = new string[]{"One","Two","Three","Four","Five"};
clojure
(def a '[One Two Three Four Five])
groovy
list = ['One', 'Two', 'Three', 'Four', 'Five']
// other variations
List<String> numbers1 = ['One', 'Two', 'Three', 'Four', 'Five']
String[] numbers2 = ['One', 'Two', 'Three', 'Four', 'Five']
numbers3 = new LinkedList(['One', 'Two', 'Three', 'Four', 'Five'])
numbers4 = ['One', 'Two', 'Three', 'Four', 'Five'] as Stack // Groovy 1.6+

Join the elements of a list, separated by commas

Given the list [Apple, Banana, Carrot] produce "Apple, Banana, Carrot"
php
$string = implode(", ", $fruits);
erlang
Result = string:join(Fruit, ", "),
Result = lists:foldl(fun (E, Acc) -> Acc ++ ", " ++ E end, hd(Fruit), tl(Fruit)),
Result = lists:flatten([ hd(Fruit) | [ ", " ++ X || X <- tl(Fruit)]]).
csharp
using System.Collections.Generic;
public class JoinEach {
public static void Main() {
var list = new List<string>() {"Apple", "Banana", "Carrot"};
System.Console.WriteLine( string.Join(", ", list.ToArray()) );
}
}
clojure
(apply str (interpose ", " '("Apple" "Banana" "Carrot")))
groovy
string = fruit.join(', ')
string = fruit.toString()[1..-2]

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([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
erlang
io:format("~s~n", [join(Fruit)]).

% ------

join([]) -> "";
join([W|Ws]) -> join(Ws, W).

join([], S) -> S;
join([W], S) -> join([], S ++ " and " ++ W);
join([W|Ws], S) -> join(Ws, S ++ ", " ++ W).
%% According to the reference manual, "string is not a data type in Erlang."
%% Instead it has lists of integers. But I/O functions in general accept
%% IO lists, where an IO list is either a list of IO lists or an integer.
%% This gives you O(1) string concatenation.

-module(commalist).
-export([join/1]).

join([]) -> "";
join([W]) -> W;
join([W1, W2]) -> [W1, " and ", W2];
join([W1, W2, W3]) -> [W1, ", ", W2, ", and ", W3];
join([W1|Ws]) -> [W1, ", ", join(Ws)].

csharp
using System.Collections.Generic;
using System.Linq;

public class CSharpListToEnglishList {
public string JoinAsEnglishList (List<string> words) {
switch (words.Count) {
case 0: return "";
case 1: return words[0];
case 2: return string.Format("{0} and {1}", words.ToArray());
default:
return JoinAsEnglishList( new List<string>() {
string.Join(", ", words.Take(words.Count - 1).ToArray()) + ",",
words.Last()
});
}
}
// Driver...
public static void Main() {
var joiner = new CSharpListToEnglishList();
System.Console.WriteLine(
joiner.JoinAsEnglishList(new List<string>() { "Apple", "Banana", "Carrot", "Orange" }) );
System.Console.WriteLine(
joiner.JoinAsEnglishList(new List<string>() { "Apple", "Banana", "Carrot" }) );
System.Console.WriteLine(
joiner.JoinAsEnglishList(new List<string>() { "One", "Two" }) );
System.Console.WriteLine(
joiner.JoinAsEnglishList(new List<string>() { "Lonely" }) );
System.Console.WriteLine(
joiner.JoinAsEnglishList(new List<string>()) );
}
}
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)))))))))
(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)))))
groovy
def join(list) {
if (!list) return ''
switch(list.size()) {
case 1:
return list[0]
case 2:
return list.join(' and ')
default:
return list[0..-2].join(', ') + ', and ' + list[-1]
}
}
ArrayList.metaClass.joinEng = { ->
def closureMap = [0: { -> delegate.join(' and ')}, 1 : {-> delegate.join(' and ')}].withDefault { k -> { -> delegate[0..-2].join(', ') + ', and ' + delegate[-1] } }
if (delegate.size()) closureMap[delegate.size()-1].call()
else ""
}

assert ["a"].joinEng() == "a"
assert ["a", "b"].joinEng() == "a and b"
assert ["a", "b", "c"].joinEng() == "a, b, and c"
assert [].joinEng() == ""

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);
}
}
erlang
Combinations =
lists:foldl(fun (Number, Acc) -> Acc ++ lists:map(fun (Letter) -> {Letter, Number} end, Letters) end, [], Numbers),
Combinations = lists:keysort(2, sofs:to_external(sofs:product(sofs:set(Letters), sofs:set(Numbers))))
[[A, B] || A <- ["a", "b", "c"], B <- [4, 5]].

csharp
using System.Collections.Generic;
public class ListCombiner {
public static void Main() {
var letters = new List<char>() { 'a', 'b', 'c' };
var numbers = new List<int>() { 1, 2, 3 };

// result is a list that contaings lists of objects
var result = new List<List<object>>();
foreach (var l in letters) {
foreach (var n in numbers) {
result.Add(new List<object>() { l, n });
}
}
}
}
clojure
(defn combine [lst1 lst2]
(mapcat (fn [x] (map #(list % x) lst1)) lst2))
(mapcat (fn [x] (map #(list % x) ["a", "b", "c"])) [4, 5])
groovy
letters = ['a', 'b', 'c']
numbers = [4, 5]
combos = [letters, numbers].combinations()

From a List Produce a List of Duplicate Entries

Taking a 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);
$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);
<?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;
}
);
?>
erlang
{_, Result} = lists:foldl(
fun(X, {Uniq, Dupl}) -> case lists:member(X, Uniq) of
true -> {Uniq,[X | Dupl]};
_ -> {[X | Uniq], Dupl}
end
end,
{[], []},
List),
Fun = fun
([X | Xs], F) -> case lists:member(X, Xs) of
true -> [X | F(Xs, F)];
_ -> F(Xs, F)
end;
([], _) -> []
end,
Result = Fun(List, Fun).
csharp
List<String> values = new List<string> {"andrew", "bob", "chris", "bob"};

var duplicates = values
.GroupBy(i => i)
.Where(j => j.Count() > 1)
.Select(s => s.Key);
foreach (var duplicate in duplicates)
{
Console.WriteLine(duplicate);
}
clojure
(->> '("andrew" "bob" "chris" "bob")
(group-by identity)
(filter #(> (count (second %)) 1))
(map first))
groovy
def input = ["andrew", "bob", "chris", "bob"]

def output = input.findAll{input.count(it)>1}.unique()

assert output == ["bob"]

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];
erlang
Result = lists:nth(3, List),
Result = element(3, list_to_tuple(List)),
{Left, _} = lists:split(3, List), Result = lists:last(Left),
Result = nth0(2, List),
csharp
string[] items = new string[] { "One", "Two", "Three", "Four", "Five" };
List<string> list = new List<string>(items);
string third = list[2]; // "Three"
// Make sure you import the System.Linq namespace.
// This is not the preferred way of indexing if you are using Lists.
string[] items = new string[] { "One", "Two", "Three", "Four", "Five" };
IEnumerable<string> list = new List<string>(items);
string third = list.ElementAt(2); // Three
clojure
(nth '[One Two Three Four Five] 2)
groovy
list = ['One', 'Two', 'Three', 'Four', 'Five']
result = list[2] // index starts at 0

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
$list = array("Red", "Green", "Blue");
$last = $list[count($list)-1];
erlang
Result = lists:last(List),
Result = last(List),
Result = hd(lists:reverse(List)),
Result = lists:nth(length(List), List),
csharp
string[] items = new string[] { "Red", "Green", "Blue" };
List<string> list = new List<string>(items);
string last = list[list.Count - 1]; // "Blue"
// Make sure you import the System.Linq namespace.
// This is not the preferred way of finding the last element if you are using Lists.
string[] items = new string[] { "Red", "Green", "Blue" };
IEnumerable<string> list = new List<string>(items);
string last = list.Last(); // "Blue"
clojure
(last '[One Two Three Four Five])
groovy
list = ['Red', 'Green', 'Blue']
result = list[-1]

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 :)
erlang
Beans = sets:from_list([broad, mung, black, red, white]), Colors = sets:from_list([black, red, blue, green]),

Common = sets:to_list(sets:intersection(Beans, Colors)),
csharp
// Make sure you import the System.Linq namespace.
// This example uses arrays as the underlying implementation, but any IEnumerable type can be used - including List.
IEnumerable<string> beans = new string[] { "beans", "mung", "black", "red", "white" };
IEnumerable<string> colors = new string[] { "black", "red", "blue", "green" };
var intersect = beans.Intersect(colors); // ['red', 'black']
clojure
(use 'clojure.set)

(let [beans '[broad mung black red white]
colors '[black red blue green]]
(intersection (set beans) (set colors)))
groovy
beans = ['broad', 'mung', 'black', 'red', 'white']
colors = ['black', 'red', 'blue', 'green']
common = beans.intersect(colors)
assert common == ['black', 'red']

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
erlang
Ages = sets:to_list(sets:from_list([18, 16, 17, 18, 16, 19, 14, 17, 19, 18])), io:format("~w~n", [Ages]).
lists:usort([18, 16, 17, 18, 16, 19, 14, 17, 19, 18]).
csharp
using System.Collections.Generic;
using System.Linq;
public class UniqueElements {
public static void Main() {
var list = new List<int>() { 18, 16, 17, 18, 16, 19, 14, 17, 19, 18 };
var uniques = list.Distinct();
}
}
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)


groovy
ages = [18, 16, 17, 18, 16, 19, 14, 17, 19, 18]
println ages.unique()
ages = [18, 16, 17, 18, 16, 19, 14, 17, 19, 18]
unique = ages as Set
println unique

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]
$list = array("Apple", "Banana", "Carrot");
array_shift($list);

// Be aware of that $list[0] is set to "Banana"
erlang
Result = tl(List),
[_|Result] = List,
N = 1, {Left, Right} = lists:split(N - 1, List), Result = Left ++ tl(Right),
Result = drop(1, List),
csharp
class Solution1516
{
static void Main()
{
List<string> fruit = new List<string>() { "Apple", "Banana", "Carrot" };
fruit.RemoveAt(0);
}
}
clojure
(let [fruit ["Apple" "Banana" "Carrot"]
index 0]
(concat
(take index fruit)
(drop (+ index 1) fruit)))
groovy
// to produce a new list
newlist = list.tail() // for 'Apple' at start
newlist = list - 'Apple' // for 'Apple' anywhere
// mutate original list
list.remove(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]
$list = array("Apple", "Banana", "Carrot");
array_pop($list);
erlang
Result = init(List),
Result = take(length(List) - 1, List),
Result = lists:reverse(tl(lists:reverse(List))),
csharp
List<string> fruits = new List() { "apple", "banana", "cherry" };
fruits.RemoveAt(fruits.Length - 1);
clojure
(pop ["Apple" "Banana" "Carrot"])
groovy
list = ['Apple', 'Banana', 'Carrot']
// to produce a new list
newlist = list[0,1]
// to modify original list
list.remove(2)

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
erlang
N = 1, {Left, Right} = lists:split(N, List), Result = Right ++ Left,
N = 1, Result = rotate(N, List),
csharp
var lst = new LinkedList<String>(new String[] {"apple", "orange", "grapes", "banana"});
lst.AddLast(lst.First());
lst.DeleteFirst();
clojure
(let [fruit ["apple" "orange" "grapes" "bananas"]]
(concat (rest fruit) [(first fruit)])
groovy
first = items.head()
items = items.tail() + first
items = items[1..-1] + items[0]
items = items + items.remove(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_map(NULL, $first, $last, $years);
erlang
First = ['Bruce', 'Tommy Lee', 'Bruce'], Last = ['Willis', 'Jones', 'Lee'], Years = [1955, 1946, 1940],

Result = lists:zip3(First, Last, Years),
csharp
String[] first = { "Bruce", "Tommy Lee", "Bruce" };
String[] last = { "Willis", "Jones", "Lee" };
int[] years = { 1955, 1946, 1940 };
var actors = first.Zip(last, (f, l) => Tuple.Create(f, l)).Zip(years, (t, y) => Tuple.Create(t.Item1, t.Item2, y)).ToArray();
Debug.Assert(actors[1].Equals(Tuple.Create("Tommy Lee", "Jones", 1946)));
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))
(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))
groovy
first = ['Bruce', 'Tommy Lee', 'Bruce']
last = ['Willis', 'Jones', 'Lee']
years = [1955, 1946, 1940]
actors = [first, last, years].transpose()
assert actors.size() == 3
assert actors[1] == ['Tommy Lee', 'Jones', 1946]

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";
}
erlang
Cards = lists:foldl(fun (Suite, Acc) -> Acc ++ lists:flatmap(fun (Face) -> [{Suite, Face}] end, Faces) end, [], Suites),

io:format("Deck has ~B cards~n", [length(Cards)]),
IsMember = lists:member({h, 'A'}, Cards),
io:format("~s~n", [if IsMember -> "Deck contains 'Ace of Hearts'" ; true -> "'Ace of Hearts' not in deck" end]),
Cards = sofs:to_external(sofs:product(sofs:set(Suites), sofs:set(Faces))),

io:format("Deck has ~B cards~n", [length(Cards)]),
IsMember = lists:member({h, 'A'}, Cards),
io:format("~s~n", [if IsMember -> "Deck contains 'Ace of Hearts'" ; true -> "'Ace of Hearts' not in deck" end]),
Deck2 = [{S, V} || S <- [d, c, h, s], V <- [2, 3, 4, 5, 6, 7, 8, 9, 10, 'J', 'Q', 'K', 'A']],
52 = length(Deck2),
true = lists:member({h, 'A'}, Deck2).

csharp
using System;
using System.Collections.Generic;
using System.Linq;

namespace Combinations
{
class Program
{
public static void Main(string[] args)
{
// Define the given lists
// Since List`1 implements the interface IEnumerable`1, this can easily be redefined as List`1.
IEnumerable<string> suites = new string[] { "H", "D", "C", "S" };
IEnumerable<string> faces = new string[] { "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K", "A" };

// LINQ Query to perform a Cartesian product and create an anonymous type to hold the results.
// "var" is required to define this as an IEnumerable`1
var deck =
from suite in suites // For each suite in suites
from face in faces // Match it with a face in face.
select new
{
Suite = suite,
Face = face
};

// Verify the count (uses LINQ extension)
if (deck.Count() == 52)
{
Console.WriteLine("Count matches!");
}

// Verify that the Ace of Hearts is in the deck (uses LINQ extension)
if (deck.Contains(new {Suite = "H", Face = "A"}))
{
Console.WriteLine("Ace of Hearts found!");
}

// Example of how to iterate through the list.
// "var" here is required since we are using an anonymous type
foreach(var card in deck)
{
Console.WriteLine("Suite: {0} Face: {1}", card.Suite, card.Face);
}

// If you desire to work with a List`1, you can convert this to a normal list at any time:
Console.WriteLine("\nConverting to list!");
var list = deck.ToList();
Console.WriteLine("Suite: {0} Face: {1}", list[5].Suite, list[5].Face);
Console.WriteLine("List count: {0}", list.Count); // 52

Console.ReadLine();
}
}
}
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
groovy
faces = ['2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K', 'A']
suites = ['H', 'D', 'C', 'S']
deck = [faces, suites].combinations()
assert deck.size() == 52
assert ['A', 'H'] in deck

Perform an operation on every item of a list

Perform an operation on every item of a list, 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'));
erlang
lists:map(fun (X) ->length(X) end, List).
csharp
using System.Collections.Generic;
public class OperationOnEach {
public static void Main() {
var list = new List<string>() { "ox", "cat", "deer", "whale" };
list.ForEach( System.Console.WriteLine );
}
}
clojure
(map count ["ox" "cat" "deer" "whale"])
groovy
animals = ["ox", "cat", "deer", "whale"]
assert animals*.size() == [2, 3, 4, 5]

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.
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;
}
}
erlang
% Wrapped call to the auxiliary function
number_split(Xs) ->
number_split(Xs, [], []).

% The auxiliary function
number_split([], Num, NonNum) ->
{Num, NonNum};
number_split([X|Xs], Num, NonNum) ->
case is_number(X) of
true ->
number_split(Xs, [X|Num], NonNum);
false ->
number_split(Xs, Num, [X|NonNum])
end.
List = ["hello", 25, 3.14, calendar:local_time()],
{Numbers, NonNumbers} = lists:partition(fun(E) -> is_number(E) end, List)
csharp
using System;
using System.Collections.Generic;
using System.Linq;

// AFAIK, there just isn't a good way to do this in C#
public class ListSplitter {
public static bool IsNumeric(object o) {
var d = new Decimal();
return decimal.TryParse(o.ToString(), out d);
}
public static void Main() {
var list = new List<object>() { "foo", DateTime.Now, 1, "bar", 2.4 };

// the Where method does the work...
var numbers = list.Where( el => IsNumeric(el) );
var nonNumbers = list.Where( el => ! IsNumeric(el) );
}

}
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)}
(group-by number? ["hello" 42 3.14 (Date.)])
groovy
now = new Date()
things = ["hello", 25, 3.14, now]
(numbers, others) = things.split{ it instanceof Number }
assert numbers == [25, 3.14]
assert others == ["hello", now]

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);
erlang
% Imperative Solution
Histogram = histogram(List),
% Functional (1) Solution
Histogram = histogram(List),
lists:foldl(fun(Elem, OldDict) ->
dict:update_counter(Elem, 1, OldDict)
end,
dict:new(),
[a,b,a,c,b,b])).
csharp
using System.Collections.Generic;
using System.Linq;

// This is a "functional" C# approach

// NOTE: In C# "maps" are of type Dictionary<Tkey, TValue>
// so our histogram map is of type Dictionary<object, int>
public class HistogramMap {
public Dictionary<object, int> FromList(List<object> list) {
// The "Aggregate" method works like "inject" in many other languages.
return list.Aggregate(
new Dictionary<object, int>(),
(map, obj) => {
// If this is the first time we've seen this obj, set the count to 0
if (!map.ContainsKey(obj)) map[obj] = 0;

// Increment the count
map[obj]++;

// Return the map for the next iteration.
// NOTE: This does NOT return from our "FromList" method
return map;
}
);
}

public static void Main() {
// Create our Histogram Map from a new list
var map = new HistogramMap().FromList(
new List<object>() { 'a', 'b', 'a', 'c', 'b', 'b' }
);

// This just prints the result
System.Console.WriteLine (
string.Join (", ",
// "Select" works like "map" or "collect" in many other languages
map.Select( kvp =>
string.Format("{0} : {1}", kvp.Key, kvp.Value)
).ToArray()
)
);
}
}
new[] {"a","b","a","c","b","b"}
.GroupBy(s => s)
.Select(s => new { Value = s.Key, Count = s.Count() })
.ToList()
.ForEach(e => Console.WriteLine("{0} : {1} ", e.Value, e.Count));
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))))))
(->> [:a :b :a :c :b :b]
(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])
groovy
histogram = [:]
list.each { item ->
if (!histogram.containsKey(item)) histogram[item] = 0
histogram[item]++
}
histogram = [:]
list.each { histogram[it] = (histogram[it] ?: 0) + 1 }

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);
erlang
% Imperative Solution
CatList = categorise(List),
% Functional (1) Solution
CatList = categorise(List),
csharp
using System.Collections.Generic;
using System.Linq;
public class ListCategorizer {
public static void Main() {
var list = new List<string>() { "one", "two", "three", "four", "five" };
var categories = list.GroupBy(el => el.Length)
.ToDictionary( g => g.Key, // key
g => g.ToList() ); // value
}
}
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)))))
(group-by count ["one" "two" "three" "four" "five"])
groovy
map = ['one', 'two', 'three', 'four', 'five'].groupBy{ it.size() }

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!";
}
erlang
if (Name == "Bob") -> io:format("Hello, ~s!~n", [Name]) ; true -> false end.
case Name of "Bob" -> io:format("Hello, ~s!~n", [Name]) ; _ -> false end.
Name == "Bob" andalso (begin io:format("Hello, ~s!~n", [Name]), true end).
csharp
if (name == "Bob") Console.WriteLine("Hello, {0}!", name);
clojure
(def person "Bob")
(if (= person "Bob")
(println "Hello, Bob!"))
groovy
if (name=='Bob')
println "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($age < 42) {
echo "You are young";
} else {
echo "You are old";
}
echo "You are " . (($age < 43) ? "young" : "old");
erlang
if Age > 42 -> io:format("You are old~n") ; true -> io:format("You are young~n") end.
Message = if Age > 42 -> "old" ; true -> "young" end, io:format("You are ~s~n", [Message]).
case Age > 42 of true -> io:format("You are old~n") ; false -> io:format("You are young~n") end.
case Age of _ when Age > 42 -> io:format("You are old~n") ; _ -> io:format("You are young~n") end.
Message = case Age of _ when Age > 42 -> "old" ; _ -> "young" end, io:format("You are ~s~n", [Message]).
Age > 42 andalso (begin io:format("You are old~n"), true end) orelse (begin io:format("You are young~n"), true end).
(fun (X) when X > 42 -> io:format("You are old~n"); (_) -> io:format("You are young~n") end)(Age).
(fun () when Age > 42 -> io:format("You are old~n"); () -> io:format("You are young~n") end)().
io:format("You are ~s~n", [if Age > 42 -> "old" ; true -> "young" end]).
csharp
int age = 41;

if (age > 42)

System.Console.WriteLine("You are old");
else
System.Console.WriteLine("You are young");


clojure
(def age 41)
(if (> age 42) "You are old" "You are young")
groovy
if (age > 42)
println "You are old"
else
println "You are young"
println "You are " + (age > 42 ? "old" : "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;
erlang
if
Age > 84 -> io:format("You are really ancient~n");
Age > 30 -> io:format("You are middle-aged~n");
true -> io:format("You are young~n")
end.
case Age of
_ when Age > 84 -> io:format("You are really ancient~n");
_ when Age > 30 -> io:format("You are middle-aged~n");
true -> io:format("You are young~n")
end.
csharp
if (age > 84) Console.WriteLine("You are really ancient");
else if (age > 30) Console.WriteLine("You are middle-aged");
else Console.WriteLine("You are young");
Console.WriteLine("You are {0}", ((age > 84) ? "really ancient" : (age > 30) ? "middle-aged" : "young"));
clojure
(println
(condp <= age
84 "You are really ancient"
30 "You are middle aged"
"You are young"))
groovy
if (age > 84)
println "You are really ancient"
else if (age > 30)
println "You are middle-aged"
else
println "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";
}
erlang
Suffix = case Num of
N when N > 10, N < 20 -> "th";
N when N rem 10 =:= 1 -> "st";
N when N rem 10 =:= 2 -> "nd";
N when N rem 10 =:= 3 -> "rd";
_ -> "th"
end,
io_lib:format("~w~s", [Num, Suffix])
csharp
public static string GetOrdinal(int i)
{
if (i > 10 && i < 20) return i.ToString() + "th";
switch (i % 10)
{
case 1:
return i.ToString() + "st";
case 2:
return i.ToString() + "nd";
case 3:
return i.ToString() + "rd";
default:
return i.ToString() + "th";
}
}
public static string GetOrdinal(int i)
{
if (i > 10 && i < 20) return i.ToString() + "th";
switch (i % 10)
{
case 1:
return i.ToString() + "st";
break;
case 2:
return i.ToString() + "nd";
break;
case 3:
return i.ToString() + "rd";
break;
default:
return i.ToString() + "th";
break;
}
}
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")))))
groovy
def suffix(n) {
switch(n) {
case { n % 100 in 4..20 } : return 'th'
case { n % 10 == 1 } : return 'st'
case { n % 10 == 2 } : return 'nd'
case { n % 10 == 3 } : return 'rd'
default : return 'th'
}
}
(1..40).each { n ->
println "$n${suffix(n)}"
}

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;
}
$x = 0;
$c = pow(2, $x);
while($c < 150) {
echo "$c,";
$c = pow(2, $x++);
}
erlang
X = 1, print_while_X_less_150(X).
Pred = fun (X) -> X < 150 end,
Action = fun (X) -> io:format("~B,", [X]), X * 2 end,
X = 1,

while_do(Pred, Action, X).
csharp
int x = 1;

while (x < 150)
{
x *= 2;
Console.Write("{0},", x);
}
clojure
(take-while #(< % 150) (iterate #(* 2 %) 1))
groovy
x = 1
while (x < 150) {
print x + ","
x *= 2
}
println()

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);
erlang
Pred = fun (DiceRoll) -> DiceRoll =/= 6 end,
Action = fun (DiceRoll) -> io:format("~B,", [DiceRoll]), dice_roll() end,

do_while(Pred, Action, dice_roll()).
-module(dice).
-export([start/0]).

start() ->
roll(dice_roll()).

roll(6) ->
io:format("6~n", []);
roll(N) ->
io:format("~B,", [N]),
roll(dice_roll()).

dice_roll() -> random:uniform(6).
csharp
System.Random die = new System.Random();
int roll;

do
{
roll = die.Next(1, 6);
Console.Write(roll);
if (roll < 6) Console.Write(",");
}
while (roll != 6);
clojure
(loop [r (rand-int 6)]
(if (= r 5)
nil
(do
(println r)
(recur (rand-int 6)))))
groovy
// Groovy has no do..while; use a normal while
int dice = 0
while (dice != 6) {
dice = Math.random() * 6 + 1
print dice
if (dice != 6) print ','
}

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";
}
erlang
dotimes(5, fun () -> io:format("Hello") end).
lists:foreach(fun (_) -> io:format("Hello") end, lists:seq(1, 5)).
csharp
string text = "Hello";

for (int i = 0; i < 5; i++)
{
Console.Write(text);
}
clojure
(dotimes [_ 5]
(print "Hello"))
groovy
println "Hello" * 5
5.times { print "Hello" }; println()

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!";
erlang
fromto(10, 1, -1, fun (X) -> io:format("~B .. ", [X]) end), io:format("Liftoff!~n").
lists:foreach(fun (X) -> io:format("~B .. ", [X]) end, lists:seq(10, 1, -1)), io:format("Liftoff!~n").
csharp
for (int i = 10; i > 0; i--)
{
Console.Write("{0} .. ", i);
}

Console.WriteLine("Liftoff!");
clojure
(dotimes [i 10]
(print (str (- 10 i) " .. ")))

(println "Liftoff!")
groovy
10.downto(1) { print it + " .. " }
println "Liftoff!"

Read the contents of a file into a string

php
$file_contents = file_get_contents("file.txt");
erlang
Text = readfile("Solution607.erl"),
Text = readfile("Solution608.erl"),
csharp
string contents = System.IO.File.ReadAllText("filename.txt");
clojure
(slurp "/tmp/foobar")
groovy
contents = file.text

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
php
$lines = file('file.txt');
foreach ($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;
}
?>
erlang
Reader = fun (IODevice) -> io:get_line(IODevice, "") end,
Worker = fun (Line, N) -> io:format("~B> ~s", [N, Line]), N + 1 end,

while_not_eof("Solution609.erl", Reader, Worker, 1).
Reader = fun (Filename) -> {ok, Contents} = file:read_file(Filename), Contents end,
Transformer = fun (Line, N) -> string:concat(string:concat(integer_to_list(N), "> "), Line) end,
Printer = fun (Line) -> io:format("~s~n", [Line]) end,

Lines = string:tokens(binary_to_list(Reader("Solution610.erl")), "\n"),
NewLines = lists:zipwith(Transformer, Lines, lists:seq(1, length(Lines))),
lists:foreach(Printer, NewLines).
csharp
int counter = 0;

// If the file is large, you would want to buffer this instead of reading everything at once
foreach (string line in System.IO.File.ReadAllLines("filename.txt"))
{
Console.WriteLine("{0}> {1}", ++counter, line);
}
clojure
(defn read-line-by-line [fn]
(reduce str (map (partial format "%d> %s\n")
(iterate inc 1)
(read-lines fn))))
groovy
int count = 0
file.eachLine { line ->
println "${++count} > $line"
}
file.eachLine { line, count ->
println "${++count} > $line"
}

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);
}
<?php
file_put_contents('file.txt', 'a string');
?>
erlang
Line = "This line overwites file contents!\n",
{ok, IODevice} = file:open("test.txt", [write]), file:write(IODevice, Line), file:close(IODevice).
csharp
System.IO.File.WriteAllText("filename.txt", "Some text to write to the file");
clojure
(with-out-writer "output.txt" (println "Hello file!"))
groovy
file.delete()
file << 'some text'
file.text = 'some text'

Append to a file

php
<?php
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);
?>
erlang
Line = "This line appended to file!\n",
{ok, IODevice} = file:open("test.txt", [append]), file:write(IODevice, Line), file:close(IODevice).
csharp
System.IO.File.AppendAllText("filename.txt", "Some text to append to the file");
clojure
(with-out-append-writer "output.txt" (println "This is appended to the file"))
groovy
file << 'some text'

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
}
erlang
% File basenames only - many tasks require absolute paths to work
lists:foreach(fun (FileOrDirPath) -> Worker(FileOrDirPath) end, file:list_dir(Directory)).
% Absolute paths provided - will accomodate most tasks
lists:foreach(fun (FileOrDirPath) -> Worker(FileOrDirPath) end, list_dir_path(Directory)).
csharp
foreach (string filename in System.IO.Directory.GetFiles(directory)) ProcessFile(filename);
clojure
; (defn process-file [f] "process one file" body...)
(map process-file (.listFiles (File. ".")))
groovy
dir.eachFile{ f -> process(f) }

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
erlang
% AFAIK, no datetime-parsing library exists; 'parse_to_datetime' is a simplistic, problem-specific hack
LocalDateTime = erlang:universaltime_to_localtime(parse_to_datetime("2008-05-06 13:29:34")),
csharp
DateTime parsedDate = DateTime.Parse("2008-05-06 13:29");
// Ideally, you would catch the potential FormatException or use DateTime.TryParse in production code.
clojure
(.. (SimpleDateFormat. "yyyy-MM-dd HH:mm")
(parse "2008-05-06 13:29"))
groovy
def date = new SimpleDateFormat("yyy-MM-dd HH:mm").parse("2008-05-06 13:29")
def date = Date.parse("yyy-MM-dd HH:mm", "2008-05-06 13:29")

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.
php
echo date('r') . "\n";
$d = new DateTime();
echo $d->format('r') . "\n";
erlang
io:format("~p~n", [calendar:local_time()])
csharp
// Creating a variable first:
DateTime now = DateTime.Now;
Console.WriteLine(now);

// Without creating a variable:
Console.WriteLine(DateTime.Now);
clojure
(import 'java.util.Date)

(println (str (Date.)))
groovy
println new Date()
OOP

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();
erlang
Greeter = make_greeter("world!"),
Greeter(greet).
csharp
using System;

class Greeter
{
private string name {get;set;}

public void Greet(){
Console.WriteLine("Hello, {0}",name);
}

public Greeter(string name){
this.name = name;
}
}

class Test
{
static void Main()
{
new Greeter("Dante").Greet();
}
}
clojure
(defprotocol IGreeter
(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"))
groovy
// version using named parameters
class Greeter {
def whom
def greet() { println "Hello, $whom" }
}
new Greeter(whom:'world').greet()
// version using traditional constructor
class Greeter {
private whom
Greeter(whom) { this.whom = whom }
def greet() { println "Hello, $whom" }
}
new Greeter('world').greet()
XML

Process an XML document

Given the XML Document:

<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;
$filename = "shop.xml";
if (($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
}
erlang
-include_lib("xmerl/include/xmerl.hrl").
-export([get_total/1]).

get_total(ShoppingList) ->
{XmlElt, _} = xmerl_scan:string(ShoppingList),
Items = xmerl_xpath:string("/shopping/item", XmlElt),
Total = lists:foldl(fun(Item, Tot) ->
[#xmlAttribute{value = PriceString}] = xmerl_xpath:string("/item/@price", Item),
{Price, _} = string:to_float(PriceString),
[#xmlAttribute{value = QuantityString}] = xmerl_xpath:string("/item/@quantity", Item),
{Quantity, _} = string:to_integer(QuantityString),
Tot + Price*Quantity
end,
0, Items),
io:format("$~.2f~n", [Total]).
csharp
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
doc.LoadXml(
@"<shopping>
<item name='bread' quantity='3' price='2.50'/>
<item name='milk' quantity='2' price='3.50'/>
</shopping>");

string decimalSeparator= System.Globalization.CultureInfo.CurrentCulture.NumberFormat.CurrencyDecimalSeparator;

double sum=0;

foreach(System.Xml.XmlNode nodo in doc.SelectNodes("/shopping/item")){
sum += int.Parse(nodo.Attributes["quantity"].InnerText) * double.Parse(nodo.Attributes["price"].InnerText.Replace(".",decimalSeparator));
}
Console.WriteLine("{0:#.00}",sum);
clojure
(println (format "Total cost of items are $%#.2f"
(->> (xml-seq (parse *xml-input-stream*))
(filter #(= :item (:tag %))) ; Remove all but the item tags
(map :attrs) ; Keep the attributes
(map (fn [e] (str "(* " (:quantity e) " " (:price e) ")"))) ; Get the total price as a sexp
(map read-string) ; "(* quantity price)" -> (* quantity price)
(map eval) ; (* quantity price) -> quantity*price
(apply +)))) ; Sum all elements
groovy
printf '$%.2f\n', new XmlSlurper().parseText(xml).item.collect{
it.@quantity.toInteger() * it.@price.toFloat()
}.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="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";
erlang
to_xml(ShoppingList) ->
Items = lists:map(fun(L) ->
[Name, Quantity, Price] = string:tokens(L, ","),
{item, [{name, Name}, {quantity, Quantity}, {price, Price}], []}
end, string:tokens(ShoppingList, "\n")),
xmerl:export_simple([{shopping, [], Items}], xmerl_xml).
csharp
string cvs ="bread,3,2.50\nmilk,2,3.50";
IList<string> rows = cvs.Split('\n');

System.Text.StringBuilder sb = new System.Text.StringBuilder("<shopping>");
foreach(string row in rows){
IList<string> data = row.Split(',');
sb.AppendFormat("<item name='{0}' quantity='{1}' price='{2}' />",data[0],data[1],data[2]);
}
sb.Append("</shopping>");
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*))
groovy
b = new groovy.xml.MarkupBuilder()
b.shopping {
csv.eachLine { line ->
(n, q, p) = line.split(',')
item(name:n, quantity:q, price:p)
}
}
// Groovy equivalent of Java JAXB solution
@XmlAccessorType(NONE)
class Item {
@XmlAttribute String name
@XmlAttribute Integer quantity
@XmlAttribute Double price
}

@XmlAccessorType(NONE)
@XmlRootElement
class Shopping {
@XmlElement Set<Item> items = []
}

Shopping shopping = new Shopping()
csvtext.eachLine{ line ->
(n, q, p) = line.split(',')
shopping.items << new Item(name:n, quantity:q.toInteger(), price:p.toDouble())
}
JAXB.marshal shopping, System.out