How to modify the key name in php (a brief analysis of built-in functions)

PHP is a widely used scripting language and is currently used by many websites. PHP is very friendly to arrays and provides support for adding, deleting, modifying, and checking arrays. During the development process, we often encounter situations where we need to change the key names of arrays. In this article, we will discuss the functions for modifying key names in PHP.

The functions to modify key names in PHP are:

1. array_combine()
2. array_flip()
3. array_replace_key()
4. array_replace()

Let’s look at their specific usage one by one.

1. array_combine()

array_combine() function can combine two arrays into one array, and use the value in one array as the key name, and the value in the other array value as the value. For example:

<?php
$keys = array(&#39;a&#39;, &#39;b&#39;, &#39;c&#39;);
$values = array(1, 2, 3);
$new_array = array_combine($keys, $values);
print_r($new_array);
?>

The result is:

Array
(
    [a] => 1
    [b] => 2
    [c] => 3
)

As you can see, the function generates a new array by using the value in the $keys array as the key name and the value in the $values ​​array as the value. . This is how array_combine() modifies key names.

2. array_flip()

array_flip() function can reverse the keys and values ​​of an array, that is, the original key names become values, and the original values ​​become is the key name. For example:

<?php
$oldArray = array(&#39;name&#39; => 'Alice', 'age' => 18);
$newArray = array_flip($oldArray);
print_r($newArray);
?>

The result is:

Array
(
    [Alice] => name
    [18] => age
)

You can see that the key name in $oldArray becomes the value in $newArray, and the value in $oldArray becomes the value in $newArray Key name. If there are duplicate values ​​in the original array, the subsequent key names will overwrite the previous key names.

3. array_replace_key()

array_replace_key() function can replace all the key names in one array with the corresponding key names in another array. For example:

<?php
$array = array(&#39;a&#39; => 1, 'b' => 2, 'c' => 3);
$newArray = array_replace_key(array('b' => 'x'), $array);
print_r($newArray);
?>

The result is:

Array
(
    [a] => 1
    [x] => 2
    [c] => 3
)

You can see that the $b key name in the $array array is replaced with $x, and a new array $newArray is generated.

4. array_replace()

array_replace() function can replace the values ​​in one or more arrays with the values ​​in another or multiple arrays. If there are duplicate key names, the values ​​in the subsequent array will overwrite the values ​​in the previous array. For example:

<?php
$array1 = array(&#39;a&#39; => 1, 'b' => 2);
$array2 = array('b' => 'x', 'c' => 3);
$newArray = array_replace($array1, $array2);
print_r($newArray);
?>

The result is:

Array
(
    [a] => 1
    [b] => x
    [c] => 3
)

You can see that the values ​​in the $array1 and $array2 arrays are merged into a new array $newArray, and the $b key in $array2 The name overwrites the $b key name in $array1.

The above are the functions for modifying key names in PHP. These functions can help us quickly and easily modify the key names in the array. Of course, we must also be very careful not to destroy the original structure and logic of the array when using these functions.

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