How to change the value in an array in php

PHP array is a very powerful data type that allows us to store multiple values ​​in one variable. In practical applications, we often need to modify the values ​​in the array to meet the needs of the program. In this article, we will explain how to change the values ​​in an array in PHP.

1. Modify the array value through the key name

PHP arrays have two storage methods: index array and associative array. For an indexed array, we can access its elements through the subscript (key name), and for an associative array, we can access its elements through the key (key name). Therefore, if we want to modify the value in the array, the simplest way is to access the array element according to the subscript or key name and modify its value.

For example, we have an array $a, with elements 1, 2, 3, and 4. If we want to change the value of the first element to 5, we can do it as follows:

$a = array(1, 2, 3, 4);
$a[0] = 5;

If we have an associative array $b with the keys 'name', 'age', 'gender ', the corresponding values ​​are 'Zhang San', 20, 'Male', we can modify the value in the following way:

$b = array('name' => '张三', 'age' => 20, 'gender' => '男');
$b['age'] = 25;

2. Delete and insert elements through the array_splice() function

What if we want to delete an element from the array and insert a new element at that position? At this time, we can use PHP's built-in function array_splice() to achieve this.

The syntax of the array_splice() function is as follows:

array_splice(array &$input , int $offset [, int $length = 0 [, mixed $replacement ]]): array

Among them, $input represents the array to be operated on; $offset represents the starting position to be deleted and inserted; $length represents the element to be deleted Quantity, defaults to 0 if omitted; $replacement is an optional array of new elements representing the elements to be inserted. Finally, the function returns the modified array.

For example, if we have an array $c with elements 1, 2, 3, 4, 5, and now want to delete the second element 2 and insert 6 at that position, we can do it as follows Perform the operation:

$c = array(1, 2, 3, 4, 5);
array_splice($c, 1, 1, 6);

After executing the above code, the $c array will become 1, 6, 3, 4, 5.

3. Replace element values ​​through the array_replace() function

If we want to replace all element values ​​in the array that meet a certain condition with new element values, we can use the PHP built-in function array_replace ()to fulfill.

The syntax of the array_replace() function is as follows:

array_replace(array $array , array …$args): array

Among them, $array represents the array to be operated on; $args is a variable parameter, in which multiple arrays can be entered to represent the array to be replaced. element. Finally, the function returns the modified array.

For example, if we have an array $d with elements 1, 2, 3, 4, 5, and now want to replace all odd numbers with 10, we can do it as follows:

$d = array(1, 2, 3, 4, 5);
$d_new = array_replace($d, array_fill_keys(array_keys($d,1) + array_keys($d,3) + array_keys($d,5), 10));

After executing the above code, the $d_new array will become 10, 2, 10, 4, 10.

To sum up, we can modify the values ​​in the PHP array in the above three ways. Mastering these methods will help us implement complex program logic more efficiently.

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