How to change the key value of an array in php

In PHP, array is a very common variable type and is often used when processing data. In many cases we need to change the key value of an array, that is, replace an existing key value with another, or merge multiple key values ​​into one. In this article, we will introduce several ways to change the key value of an array in PHP.

1. Use the array_replace function

The array_replace function can be used to replace the key values ​​in an array. It replaces the keys in the second array with the corresponding keys in the first array and returns a new array.

Sample code:

$arr1 = array('key1' => 'value1', 'key2' => 'value2');
$arr2 = array('key1' => 'new_value', 'key3' => 'value3');

$new_arr = array_replace($arr1, $arr2);

print_r($new_arr);

The results are as follows:

Array
(
    [key1] => new_value
    [key2] => value2
    [key3] => value3
)

In the above sample code, we define two arrays $arr1 and $arr2, where $arr2 The 'key1' key value is replaced with 'new_value'. After using the array_replace function to merge the two arrays, the original 'key1' key value in $arr1 was replaced with 'new_value', and a new key value 'key3' was added.

2. Use the array_combine function

The array_combine function can combine the key values ​​​​in two arrays into a new array. Among them, the keys of the first array are used as the keys of the new array, and the values ​​of the second array are used as the values ​​of the new array.

Sample code:

$keys = array('key1', 'key2', 'key3');
$values = array('value1', 'value2', 'value3');

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

print_r($new_arr);

The results are as follows:

Array
(
    [key1] => value1
    [key2] => value2
    [key3] => value3
)

In the above sample code, we defined two arrays $keys and $values, which are key names and keys respectively. value. After using the array_combine function to combine two arrays, the elements in $keys are used as the keys of the new array, and the elements in $values ​​are used as the keys of the new array.

Normally, the number of elements in the $keys and $values ​​arrays should be the same, otherwise an error will occur.

3. Use the array_flip function

The array_flip function can interchange the key values ​​and key names in the array, that is, the key values ​​in the original array become the key names of the new array, and the original array The key names in become the key values ​​of the new array. It should be noted that the key names in the original array must be unique, otherwise an error will occur.

Sample code:

$arr = array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3');

$new_arr = array_flip($arr);

print_r($new_arr);

The results are as follows:

Array
(
    [value1] => key1
    [value2] => key2
    [value3] => key3
)

In the above sample code, we define an array $arr and use the array_flip function to flip the keys in $arr After the values ​​and key names are exchanged, the original key value 'key1' is turned into the key name of the new array, and the original key name 'value1' is turned into the key value of the new array. Similarly, 'key2' is turned into the key name of the new array, and 'value2' is turned into the key value of the new array, and 'key3' and 'value3' are also turned into the key name and key value of the new array respectively. .

Summary:

In this article, we introduced three methods of changing array key values ​​in PHP, using the three functions array_replace, array_combine, and array_flip. The appropriate method needs to be chosen based on specific needs. No matter which method is used, you need to pay attention to the number of elements and the uniqueness of the key names in the original array to avoid errors in the code. By learning these methods, we can handle arrays in PHP more flexibly, thereby better completing data processing work.

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