PHP array key value swap: choosing the best solution

There are three optimal solutions for key-value swapping in PHP: array_flip() function can quickly swap arrays of unique keys and values; array_combine() function merges two arrays to form a new array; custom functions can be used to customize repetitions Advanced requirements such as value processing. Choosing the best solution depends on key value uniqueness, number of duplicate values, and efficiency considerations.

PHP array key-value swapping: choosing the best solution

In PHP, there is a very high demand for array key-value swapping common. This article will explore several of the most effective methods and provide practical examples for detailed explanation.

Method 1: Use the array_flip() function

array_flip() is a built-in function that can interchange the keys and values ​​of the array. The syntax is as follows:

$new_array = array_flip($array);

Advantages:

• Simple and efficient.
• Do not modify the original array.

Disadvantages:

• Requires uniqueness of value. If duplicate values ​​exist, an overwrite situation will result.

Practical case:

Suppose we need to ['name' => 'John', 'age' => 30] Swap the key values ​​of the array.

$array = ['name' => 'John', 'age' => 30];
$new_array = array_flip($array);

foreach ($new_array as $key => $value) {  // 遍历新数组
    echo "$key: $value<br>";
}

Output:

John: name
30: age

Method 2: Use array_combine() function

array_combine() The function can use two Array generates a new array with one array as keys and another array as values. The syntax is as follows:

$new_array = array_combine($keys, $values);

Advantages:

• Allows the use of duplicate values ​​as keys or values.

Disadvantages:

• Need to prepare two separate arrays.

Practical case:

Suppose we need to change the key to ['John', 'Mary'] and the value to ## The two arrays of #[30, 25] are combined into a new array.

$keys = ['John', 'Mary'];
$values = [30, 25];
$new_array = array_combine($keys, $values);

foreach ($new_array as $key => $value) {  // 遍历新数组
    echo "$key: $value<br>";
}

Output:

John: 30
Mary: 25

Method 3: Use custom function

We can also write our own function to realize the key-value swap function. The syntax is as follows:

function flip_array($array) {
    $new_array = [];
    foreach ($array as $key => $value) {
        $new_array[$value] = $key;
    }
    return $new_array;
}

Advantages:

Customizable behavior (for example, handling duplicate values).

Disadvantages:

Lower efficiency, especially for large arrays.

Practical case:

We can use this custom function to reverse

['name' => 'John', 'age' => 30] Key value of the array.

function flip_array($array) {  // 使用自定义函数
    $new_array = [];
    foreach ($array as $key => $value) {
        $new_array[$value] = $key;
    }
    return $new_array;
}

$array = ['name' => 'John', 'age' => 30];
$new_array = flip_array($array);

foreach ($new_array as $key => $value) {  // 遍历新数组
    echo "$key: $value<br>";
}

Output:

John: name
30: age

Select the best solution

The choice of the best solution depends on the specific needs:

• Unique key value: Use array_flip().
• Allow duplicate values: Use array_combine().
• Custom processing: Use custom functions.

Consider efficiency based on the following factors:

Array size:
• array_flip() and array_combine() are generally faster.
Number of duplicate values: More duplicate values ​​will reduce the efficiency of the custom function.

The above is the detailed content of PHP array key value swap: choosing the best solution. For more information, please follow other related articles on the PHP Chinese website!