PHP Functions

$y = 1; $fn1 = fn($x) => $x + $y; // equivalent to using $y by value: $fn2 = function ($x) use ($y) { return $x + $y; }; echo $fn1(5); # => 6 echo $fn2(5); # => 6 

function coffee($type = "cappuccino") { return "Making a cup of $type.\n"; } # => Making a cup of cappuccino. echo coffee(); # => Making a cup of . echo coffee(null); # => Making a cup of espresso. echo coffee("espresso"); 

function recursion($x) { if ($x < 5) { echo "$x"; recursion($x + 1); } } recursion(1); # => 1234 

$greet = function($name) { printf("Hello %s\r\n", $name); }; $greet('World'); # => Hello World $greet('PHP'); # => Hello PHP 

function bar($arg = '') { echo "In bar(); arg: '$arg'.\n"; } $func = 'bar'; $func('test'); # => In bar(); arg: test 

// Available in PHP 7.1 function voidFunction(): void { echo 'Hello'; return; } voidFunction(); # => Hello 

// Available in PHP 7.1 function nullOrString(int $v) : ?string { return $v % 2 ? "odd" : null; } echo nullOrString(3); # => odd var\_dump(nullOrString(4)); # => NULL 

See: Nullable types

// Basic return type declaration function sum($a, $b): float {/\*...\*/} function get\_item(): string {/\*...\*/} class C {} // Returning an object function getC(): C { return new C; } 

function square($x) { return $x * $x; } echo square(4); # => 16