Using PHP array_map() Function: Syntax, Parameters, and Practical Examples

The array_map() function applies a user‑defined callback to each element of one or more arrays and returns a new array containing the transformed values.

Function signature

array_map ( callable $callback , array $array1 [, array $... ] ) : array

Parameter description

$callback

: The callback function that processes each element; it can be a named function or an anonymous function. $array1: The primary array to be processed. $...: Optional additional arrays whose elements are passed to the callback.

Return value: A new array composed of the elements returned by the callback.

Example 1 – Using a named function

The following code defines a function convert_to_uppercase() that converts a string to uppercase, then uses array_map() to apply it to an array of names.

<?php
function convert_to_uppercase($value) {
    return strtoupper($value);
}

$names = array("john", "james", "jane", "julie");
$names_uppercase = array_map("convert_to_uppercase", $names);

print_r($names_uppercase);
?>

The script prints:

Array
(
    [0] => JOHN
    [1] => JAMES
    [2] => JANE
    [3] => JULIE
)

Example 2 – Using an anonymous function

This example shows how to double each number in an array by passing an anonymous function to array_map().

<?php
$numbers = array(1, 2, 3, 4, 5);
$doubled_numbers = array_map(function($value) {
    return $value * 2;
}, $numbers);

print_r($doubled_numbers);
?>

The output is:

Array
(
    [0] => 2
    [1] => 4
    [2] => 6
    [3] => 8
    [4] => 10
)

In real‑world development, array_map() is frequently used for array transformations, filtering, or any operation where each element needs to be processed by a custom callback.