How to Reverse Arrays in PHP Using array_reverse

PHP is a powerful scripting language not only for web development but also for array manipulation. This article introduces the PHP function array_reverse for reversing the order of array elements.

Function Syntax

The syntax of array_reverse is:

array array_reverse ( array $array [, bool $preserve_keys = FALSE ] )

Parameters: $array: The array to be reversed. $preserve_keys: When FALSE (default), keys are reindexed; when TRUE, original keys are preserved.

Basic Example

The following code demonstrates reversing a simple indexed array:

<?php
// Create a simple array
$fruits = array("apple", "banana", "orange", "grape");

// Output original array
echo "Original array:";
print_r($fruits);

// Reverse the array
$reversed_fruits = array_reverse($fruits);

// Output reversed array
echo "Reversed array:";
print_r($reversed_fruits);
?>

Running this script produces:

Original array: Array
(
    [0] => apple
    [1] => banana
    [2] => orange
    [3] => grape
)
Reversed array: Array
(
    [0] => grape
    [1] => orange
    [2] => banana
    [3] => apple
)

The output shows that the elements have been successfully reversed.

Preserving Keys

If you need to keep the original keys after reversal, pass true as the second argument:

$reversed_fruits = array_reverse($fruits, true);

This technique works for both simple indexed arrays and associative arrays.

Overall, the array_reverse function provides a straightforward way to invert array order in PHP, with an optional flag to retain original keys.