How to swap keys and values ​​in PHP arrays

How PHP arrays exchange keys and values

In PHP, arrays are an important and commonly used data structure. Sometimes we need to interchange the keys and values ​​of the array to meet certain needs. This article will introduce several methods to interchange the keys and values ​​of PHP arrays, and provide corresponding code examples.

Method 1: Use the array_flip function

The array_flip function is a built-in function in PHP, which can be used to exchange the keys and values ​​of the array. The following is a code example that uses the array_flip function to interchange the keys and values ​​of the array:

$fruit = array(
    'apple' => 'red',
    'banana' => 'yellow',
    'orange' => 'orange'
);

$color = array_flip($fruit);

print_r($color);

The output result is:

Array
(
    [red] => apple
    [yellow] => banana
    [orange] => orange
)

As can be seen from the above example, using the array_flip function can be very simple Swap the keys and values ​​of the array.

Method 2: Use foreach loop

In addition to using the array_flip function, we can also use foreach loop to exchange the keys and values ​​of the array. The following is a code example that uses a foreach loop to swap the keys and values ​​of an array:

$fruit = array(
    'apple' => 'red',
    'banana' => 'yellow',
    'orange' => 'orange'
);

$color = array();

foreach ($fruit as $key => $value) {
    $color[$value] = $key;
}

print_r($color);

The output is:

Array
(
    [red] => apple
    [yellow] => banana
    [orange] => orange
)

By looping through the array and swapping the keys and values, we can get and Same result using array_flip function.

Method 3: Use array_walk function

The array_walk function is an array traversal function provided by PHP. We can modify it while traversing the array. The following is a code example that uses the array_walk function to interchange the keys and values ​​of an array:

$fruit = array(
    'apple' => 'red',
    'banana' => 'yellow',
    'orange' => 'orange'
);

$color = array();

array_walk($fruit, function ($value, $key) use (&$color) {
    $color[$value] = $key;
});

print_r($color);

The output is:

Array
(
    [red] => apple
    [yellow] => banana
    [orange] => orange
)

By passing an anonymous function to the array_walk function, we can traverse the array while Modify it so that the keys and values ​​of the array are interchanged.

Summary:

This article introduces three common methods to interchange the keys and values ​​of PHP arrays, namely using the array_flip function, using the foreach loop and using the array_walk function. Choosing the appropriate method according to the actual situation can help us realize the key-value exchange of the array and meet the corresponding needs. Hope this article is helpful to you!

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