Techniques for partially reversing a PHP array

PHP partial array reversal technology: use array_slice() and array_reverse() to intercept and reverse the array part. Use range() to generate a range of consecutive numbers, then reverse the array parts. Practical example: Reverse the price of a specific element in the array, such as reversing the price from the second to the fourth element in the product array, which can be achieved using array_slice() and array_reverse().

Technique for partially reversing a PHP array

Introduction

In many Situation where we need to reverse only partial elements of PHP array. This tutorial will introduce different techniques to achieve this.

Method 1: Use array_slice()

Use array_slice() The function can intercept a part of the elements from the array, and then use array_reverse () function to reverse it.

$array = ['a', 'b', 'c', 'd', 'e'];
$start = 1;
$length = 3;

$reversed = array_slice($array, $start, $length);
$reversed = array_reverse($reversed);

// 将反转部分插入原始数组
array_splice($array, $start, $length, $reversed);

Method 2: Use range()

range() function can generate a continuous range of numbers, which can be used to reverse the array part of the elements.

$array = ['a', 'b', 'c', 'd', 'e'];
$start = 1;
$length = 3;

$reversed = [];
for ($i = $start + $length - 1; $i >= $start; $i--) {
    $reversed[] = $array[$i];
}

// 将反转部分插入原始数组
array_splice($array, $start, $length, $reversed);

Practical case

Suppose there is an array containing product names and prices:

$products = [
    ['name' => 'Apple', 'price' => 10],
    ['name' => 'Banana', 'price' => 5],
    ['name' => 'Orange', 'price' => 7],
    ['name' => 'Grape', 'price' => 8],
    ['name' => 'Strawberry', 'price' => 9],
];

To reverse the second in the array to For the price of the fourth element, you can use the following code:

$start = 1;
$length = 3;

$reversed = array_slice($products, $start, $length);
array_reverse($reversed);
array_splice($products, $start, $length, $reversed);

The reversed array is as follows:

[
    ['name' => 'Apple', 'price' => 10],
    ['name' => 'Strawberry', 'price' => 9],
    ['name' => 'Grape', 'price' => 8],
    ['name' => 'Orange', 'price' => 7],
    ['name' => 'Banana', 'price' => 5],
]

The above is the detailed content of Techniques for partially reversing a PHP array. For more information, please follow other related articles on the PHP Chinese website!