Reverse the sequence of specified elements in a PHP array

How to reverse the specified order of elements in an array: use array_reverse() and array_merge(): start and end the reversed elements from the array, and then merge them into the original array. Use a for loop: iterate through the array and swap the positions of specified elements.

How to reverse the order of specified elements in an array in PHP

Preface

Reversing the order of specified elements in an array is a common task in PHP, such as extracting a specific part from an array or processing data in reverse order. This article will introduce several effective ways to achieve this goal.

Method 1: array_reverse()

array_reverse() function can reverse the entire array, but if you only want to reverse specific elements, The following workarounds can be used:

$arr = [1, 2, 3, 4, 5, 6];
$start = 2; // 开始反转的元素索引
$end = 4; // 结束反转的元素索引
$reversed = array_reverse($arr);
$arr = array_merge(array_slice($arr, 0, $start), $reversed, array_slice($arr, $end + 1));

Method 2: Using a for loop

You can use a for loop to iterate through the array and reverse the specified Elements:

$arr = [1, 2, 3, 4, 5, 6];
$start = 2;
$end = 4;
for ($i = $start; $i <= $end; $i++) {
    $temp = $arr[$i];
    $arr[$i] = $arr[$end];
    $arr[$end] = $temp;
    $end--;
}

Practical case

Suppose we have an array of fruits and want to reverse the order from the 2nd to the 4th element.

$fruits = ["Apple", "Orange", "Banana", "Mango", "Pear", "Grapes"];
$result = array_reverse($fruits); // 首先反转整个数组
$result = array_merge(array_slice($result, 0, 2), array_reverse(array_slice($result, 2, 3)), array_slice($result, 5)); // 然后反转指定部分
print_r($result); // 输出 ["Apple", "Orange", "Grapes", "Mango", "Banana", "Pear"]

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