How to modify array subscript value in php

For PHP developers, arrays are a commonly used data type and are often used to store and operate data of the same type. In actual applications, we will inevitably encounter situations where we need to modify the array subscript value. This article will introduce in detail how to modify the array subscript value.

1. Modify the value of the specified subscript

To modify the value of a specific subscript, you can use the following syntax:

$array[index] = new_value;

Among them, $array is the target Array, $index is the index to be modified, new_value is the value to be modified.

For example, in the following code, we will modify the value of the second item of the array $arr:

$arr = array('a', 'b', 'c');
$arr[1] = 'new_value';
print_r($arr);

The output result is:

Array
(
    [0] => a
    [1] => new_value
    [2] => c
)

It can be seen that we successfully The second item in the $arr array is changed from 'b' to 'new_value'.

2. Modify the values ​​of all subscripts

Sometimes we need to modify the subscripts of all elements of the array, so that data operations can be more convenient. The following is how to modify the array subscript:

$new_array = array_values($old_array);

Among them, $old_array is the original array, and $new_array is the modified new array. This method can use the array_values() function, which returns a new array containing all the values ​​in the array, and the subscripts of the new array are automatically assigned starting from 0.

The following example demonstrates how to use the array_values() function to modify the array subscript:

$old_array = array('a' => 1, 'b' => 2, 'c' => 3);
$new_array = array_values($old_array);
print_r($new_array);

The output result is:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)

At this time, the original array subscript a, b and c have been dropped, and the subscripts of the new array are 0, 1, and 2.

3. Exchanging subscripts

Arrays in PHP provide a very convenient function, which is to exchange elements in the array. To exchange the subscripts of two elements in the array, we can use the following code:

$arr = array('a' => 1, 'b' => 2, 'c' => 3);
$temp = $arr['a']; //保存a位置的值
$arr['a'] = $arr['b']; //将a位置的值变为b位置的值
$arr['b'] = $temp; //将b位置的值变为之前的a位置的值

The above code will exchange the subscripts of the two elements a and b in the array $arr.

Summary

It is relatively simple to modify the subscript value of an array in PHP. There are three main methods, namely modifying the value of the specified subscript, modifying the value of all subscripts and exchanging subscripts. . According to actual needs, we can choose different methods to operate arrays to improve the efficiency and readability of the program.

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