PHP converts array key values: efficiency analysis of different solutions

PHP has three most commonly used solutions for converting array key values: array_flip() function: the fastest ksort() function: suitable for situations where sort keys are required Custom iterator: efficient for small arrays

PHP Converting Array Key Values: Efficiency Analysis of Different Solutions

In PHP, converting array key values ​​is a common task. There are several different ways to do this, each with its own efficiency characteristics. This article will analyze the three most commonly used solutions: array_flip() function, ksort() function and custom iterator.

1. array_flip() Function

array_flip() The function creates a new array in which the keys and values ​​are interchanged. This is the fastest way to convert array key values:

$array = ['a' => 1, 'b' => 2, 'c' => 3];
$flipped = array_flip($array); // $flipped = [1 => 'a', 2 => 'b', 3 => 'c']

2. ksort() Function

ksort() The function performs operations on array keys Sort. Then, you can use the keys in the sorted array as the keys of the new array and the values ​​as the values ​​of the new array:

$array = ['b' => 2, 'c' => 3, 'a' => 1];
ksort($array); // $array = ['a' => 1, 'b' => 2, 'c' => 3]
$flipped = array_combine(array_keys($array), array_values($array)); // $flipped = [1 => 'a', 2 => 'b', 3 => 'c']

3. Custom iterator

You can use a custom iterator to Iterate over the original array and create a new array with the keys and values ​​interchanged:

$array = ['a' => 1, 'b' => 2, 'c' => 3];
$flipped = [];
foreach ($array as $key => $value) {
    $flipped[$value] = $key;
}

Practical Example

The following is a practical example of mapping user IDs to username arrays:

// 假设 $users 是一个关联数组，键为用户 ID，值为用户名
$userIds = [10, 20, 30];

// 使用 `array_flip()` 函数创建映射
$usernameMap = array_flip($users);

// 使用映射获取特定用户 ID 的用户名
$username = $usernameMap[20]; // 'user20'

Efficiency Analysis

In most cases, the array_flip() function is the fastest solution. However, when keys need to be sorted after conversion, the ksort() method is more suitable. A custom iterator can also be efficient for small arrays, but its efficiency decreases as the array size increases.

In general, which solution to choose depends on the specific scenario and performance requirements.

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