How to Reverse an Array in PHP?
Last Updated :
18 Jun, 2024
Reversing an array in PHP involves rearranging its elements so that the last element becomes the first, the second-to-last becomes the second, and so on. This operation is essential in various programming scenarios for altering data order or preparing data for specific operations. Implementing array reversal efficiently ensures that data manipulation tasks are executed smoothly and effectively.
Example:
Input: $array = [1,2,3,4,5];
Output: Array ( [0] => 5[1] => 4[2] => 3[3] => 2[4] => 1 )
There are several approaches to reverse an array in PHP hp which are as follows:
Using the array_reverse() function
We are going to use the $reversedArray() function to reverse the given array. Then, we have use the print_r to print the output of the same.
Example: This example shows the reverse of an array using the array_reverse() function.
PHP
<?php
$originalArray = array(1, 2, 3, 4, 5);
echo "Original Array: ";
print_r($originalArray);
echo "\n";
$reversedArray = array_reverse($originalArray);
echo "Reversed Array: ";
print_r($reversedArray);
echo "\n";
?>
OutputOriginal Array: Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
[4] => 5
)
Reversed Array: Array
(
[0] => 5
[1] => 4
[2] => 3
[3] => 2
[4] => 1
) Using a for loop
We are going to reverse an array using a loop in which we will first initialize an empty array and store the reversed elements. Then we will iterate it through the original array starting from the last element and moving towards the first element using for loop in which each iteration will append the current element to the new array. At last, the loop ends and the new array will contain the elements in reverse order.
Example: This example shows the reverse of an array using the for loop.
PHP
<?php
$originalArray = array(1, 2, 3, 4, 5);
$reversedArray = array();
$length = count($originalArray);
for ($i = $length - 1; $i >= 0; $i--) {
$reversedArray[] = $originalArray[$i];
}
echo "Original Array: ";
print_r($originalArray);
echo "\nReversed Array: ";
print_r($reversedArray);
?>
OutputOriginal Array: Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
[4] => 5
)
Reversed Array: Array
(
[0] => 5
[1] => 4
[2] => 3
[3] => 2
[4] => 1
)
Using the array_reverse() function with array_keys() and array_combine()
We are going to reverse an array using the array_reverse() function along with array_keys() and array_combine(). We use the array_keys() to get the keys of the original array and then use array_reverse() to reverse the order of the keys. At last, we use array_combine() to combine the reversed keys with the original array values and print_r to print the output.
Example: This example shows the reverse of an array Using the array_reverse() function with array_keys() and array_combine().
PHP
<?php
$originalArray = array(
'a' => 'Apple',
'b' => 'Banana',
'c' => 'Cherry',
'd' => 'Date'
);
$keys = array_keys($originalArray);
$reversedKeys = array_reverse($keys);
$reversedArray = array_combine($reversedKeys, $originalArray);
echo "Original Array:<br>";
print_r($originalArray);
echo "<br><br>Reversed Array:<br>";
print_r($reversedArray);
?>
OutputOriginal Array:<br>Array
(
[a] => Apple
[b] => Banana
[c] => Cherry
[d] => Date
)
<br><br>Reversed Array:<br>Array
(
[d] => Apple
[c] => Banana
[b] => Cherry
[a] => Dat...
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