How to change array index in php (two methods)

In PHP programming, array is a very important data type. PHP provides some built-in functions and syntax to operate arrays, such as adding, deleting, modifying, etc. Among them, changing the array index is a relatively common requirement. This article will introduce how to change the array index in PHP.

1. Use PHP’s built-in function array_flip()

PHP’s array_flip() function can be used to exchange the keys and values ​​of the array. We can use this function to exchange the keys and values ​​of the original array, then change the keys as needed, and finally exchange the keys and values ​​back to achieve the purpose of changing the array index. The following is an example:

$oldArray = array('one' => '1', 'two' => '2', 'three' => '3');
$newArray = array_flip($oldArray);

// 更改键
$newArray['newOne'] = $newArray['one'];
unset($newArray['one']);

$newArray = array_flip($newArray);

print_r($newArray);

In this example, $oldArray is the original array, and $newArray is the generated new array. First, the keys and values ​​of the original array are exchanged through the array_flip() function, and then the new key 'newOne' replaces the original 'one'. The second step is to use the unset() function to delete the original 'one' element in the array. Finally, swap the keys and values ​​of the new array back to get the new array with the changed index.

2. Use the PHP built-in function array_splice()

Another way to change the array index is to use the PHP built-in function array_splice(). This function deletes elements from an array and replaces them with new elements. This function requires two required parameters: the original array to be modified and the new array to be replaced. The following is an example:

$oldArray = array('one' => '1', 'two' => '2', 'three' => '3');
$newArray = array('newOne' => '1', 'two' => '2', 'three' => '3');

array_splice($oldArray, 0, count($oldArray), $newArray);

print_r($oldArray);

In this example, $oldArray is the original array, and $newArray is the new array to be replaced. The first parameter in the array_splice() function is the modified array, the second parameter is the subscript of the deleted element, the third parameter is the number of elements to be deleted, and the fourth parameter is to replace the original deleted element. . In this example, we delete all elements of the original array and replace the original array with the new array. Finally, the new modified array is printed out.

Summary

The above are two ways to change the array index in PHP programming. One is to use PHP's built-in function array_flip() to exchange the original array keys and values ​​before performing the operation, and finally exchange the keys and values ​​back. The other is to use the PHP built-in function array_splice() to first delete all elements of the original array and then replace them with new elements. Both methods can achieve the purpose of changing the array index. We can choose different methods to operate according to the actual situation to improve programming efficiency and code readability.

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