What is an anonymous PHP function?

Question

What is an anonymous function in PHP? Could you give me a simple example?

Answer 1

PHP.net has a page describing Anonymous Functions and on Wikipedia you can read Anonymous Functions in general.

Anonymous functions can be used to contain functionality that does not need to be named and, possibly, for short-term use. Some well-known examples include closure.

Example from PHP.net

<?php
$greet = function($name)
{
    printf("Hello %s\r\n", $name);
};

$greet('World');
$greet('PHP');
?>

PHP 4.0.1 to 5.3

$foo = create_function('$x', 'return $x*$x;');
$bar = create_function("\$x", "return \$x*\$x;");
echo $foo(10);

PHP 5.3

$x = 3;
$func = function($z) { return $z *= 2; };
echo $func($x); // prints 6

PHP 5.3 supports closure, but variables must be explicitly specified

$x = 3;
$func = function() use(&$x) { $x *= 2; };
$func();
echo $x; // prints 6

Examples taken from Wikipedia and php.net

Answer 2

Google :

http://php.net/manual/de/functions.anonymous.php

echo preg_replace_callback('~-([a-z])~', function ($match) {
    return strtoupper($match[1]);
}, 'hello-world');
// outputs helloWorld

, ( ), " ". , , , .

function foo($match) {
 return strtoupper($match[1]);
}