langref.org - php, clojure, and cpp

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Structure

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!";
}

clojure

(def person "Bob")
(if (= person "Bob")
(println "Hello, Bob!"))

cpp

if (name == "Bob") Console::WriteLine("Hello, {0}!", name);

if (name == "Bob") std::cout << "Hello, " << name << "!" << std::endl;

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");

clojure

(def age 41)
(if (> age 42) "You are old" "You are young")

cpp

if (age > 42) Console::WriteLine("You are old");
else Console::WriteLine("You are young");

Console::WriteLine("You are {0}", (age > 42 ? "old" : "young"));

std::printf("You are %s\n", (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;

clojure

(println
(condp <= age
84 "You are really ancient"
30 "You are middle aged"
"You are young"))

cpp

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"));

std::cout << "You are " << (age > 84 ? "really ancient" : age > 30 ? "middle-aged" : "young") << std::endl;

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

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")))))

cpp

#include<iostream.h>
#include<conio.h>
void main()
{
clrscr();
int num,i,x;
cout<<"Enter the range:";
cin>>num;
for(i=1;i<=num;i++)
{
x=i%10;
switch(i)
{
case 11:
case 12:
case 13:cout<<i<<"th ";
continue;
}
switch(x)
{
case 1: cout<<i<<"st ";break;
case 2: cout<<i<<"nd ";break;
case 3: cout<<i<<"rd ";break;
default: cout<<i<<"th ";
}
}
getch();
}

Loops

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++);
}

clojure

(take-while #(< % 150) (iterate #(* 2 %) 1))

cpp

int x = 1;

while (x < 150) { x *= 2; Console::Write("{0},", x); }
Console::WriteLine();

for (int x = 1; x < 150; x *= 2) { std::cout << x << ","; }
std::cout << std::endl;

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);

clojure

(loop [r (rand-int 6)]
(if (= r 5)
nil
(do
(println r)
(recur (rand-int 6)))))

cpp

Random^ rnd = gcnew Random;

int dice = rnd->Next(1, 7); Console::Write("{0}", dice);
do { Console::Write(",{0}", (dice = rnd->Next(1, 7))); } while (dice != 6);
Console::WriteLine();