How to use function pointers in PHP?

In PHP, a function pointer is a variable called a callback function that points to the function address. It allows dynamic processing of functions: Syntax: $functionPointer = 'function_name' Practical example: Perform operations on arrays: usort($numbers, 'sortAscending') as function parameters: array_map(function($string) {...}, $strings )Note: The function pointer points to the function name, which must match the specified type and ensure that the pointed function always exists.

#How to use function pointers in PHP?

A function pointer is a variable that points to the address of a function, allowing us to handle functions in a dynamic way. In PHP, function pointers are called callback functions.

Syntax

$functionPointer = 'function_name';

Practical case

Perform specific operations on arrays

We can use function pointers to perform custom operations on arrays. For example, the following code uses the usort function to sort an array of numbers in ascending order:

function sortAscending($a, $b) {
    return $a - $b;
}

$numbers = [5, 2, 8, 1, 4];
usort($numbers, 'sortAscending');

print_r($numbers); // 输出：[1, 2, 4, 5, 8]

Passing the function as a parameter

Function pointers can also be used as functions parameters. For example, the following code uses an anonymous function as a parameter of the array_map function:

$strings = ['hello', 'world', 'php'];

$mappedStrings = array_map(function($string) {
    return strtoupper($string);
}, $strings);

print_r($mappedStrings); // 输出：[HELLO, WORLD, PHP]

Note

• The function pointer points to the function name, not a reference to the function.
• The function pointed to by the function pointer must accept parameters and return values ​​consistent with the specified type.
• When using function pointers, make sure that the function pointed to by the function pointer always exists.

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