Master PHP’s array_map(): Basics, Advanced Tricks & Real‑World Examples

In PHP’s function library, the array_map() function is extremely useful for processing arrays by applying a callback to each element and returning a new array.

1. Basic usage of array_map()

The basic syntax is: array_map(callable $callback, array ...$arr) The $callback parameter is the function or method to be called for each element, and the $arr parameter represents the array(s) to be processed.

Example:

$arr = [1, 2, 3];
$newArr = array_map(function($v) {
    return $v * 2;
}, $arr);
print_r($newArr);

Running this code produces a new array where each element is multiplied by 2:

Array ( [0] => 2 [1] => 4 [2] => 6 )

2. Advanced usage of array_map()

Beyond the basic usage, array_map() can handle multiple arrays and pass additional parameters to the callback.

Processing multiple arrays:

$arr1 = [1, 2, 3];
$arr2 = [4, 5, 6];
$newArr = array_map(function($v1, $v2) {
    return $v1 + $v2;
}, $arr1, $arr2);
print_r($newArr);

The result is: Array ( [0] => 5 [1] => 7 [2] => 9 ) Passing extra parameters (e.g., a prefix) to the callback:

$arr = [1, 2, 3];
$prefix = 'num:';
$newArr = array_map(function($v, $prefix) {
    return $prefix . $v;
}, $arr, array_fill(0, count($arr), $prefix));
print_r($newArr);

The resulting array is:

Array ( [0] => num:1 [1] => num:2 [2] => num:3 )

Summary

The array_map() function is a convenient PHP tool for array manipulation; by providing different callbacks and parameters, you can perform a wide range of operations on arrays. Pay attention to the callback definition and the number of parameters passed to achieve the desired results.