How to create anonymous function of PHP function?

Anonymous functions (closures) allow functions to be defined without declaring a named function, for temporary or callback functions. Syntax: $anon_func = function (parameter list) {function body}; accepts parameters and returns a value. The function body is enclosed in brackets {}. For example: filter even numbers: $anon_func = function($num) { return $num % 2 == 0;}; $even_numbers = array_filter($numbers, $anon_func);

Creation of PHP anonymous functions

Anonymous functions are also called closures, which allow functions to be defined without declaring a named function. Anonymous functions are typically used when a temporary function or callback function is required.

Syntax

The syntax of anonymous functions in PHP is as follows:

$anon_func = function (参数列表) {
  // 函数体
};

Parameters and return values

Just like normal functions, anonymous functions can accept parameters and return a value. The function body is enclosed in brackets {}.

Practical case

The following is an example of using an anonymous function to filter an array:

$numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

$even_numbers = array_filter($numbers, function($num) {
  return $num % 2 == 0;
});

print_r($even_numbers); // 输出：[2, 4, 6, 8, 10]

In this example, we create an anonymous Function that takes a number $num and returns a Boolean value indicating whether the number is even. The array_filter() function then uses this anonymous function to filter the array $numbers, retaining only elements that meet the function's conditions.

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