How to change the value in an array in php

PHP is a popular server-side scripting language that is widely used in the field of web development. In PHP development, it is often necessary to operate and process arrays. This article will introduce how to use PHP to change the values ​​​​in an array.

1. Basic concepts of arrays

1.1 Definition of array

An array is a container used to store a set of data, in which each data item has an index value. We can access a data item in the array through this index value. In PHP, arrays can be defined in many ways, for example:

$array1 = array(1, 2, 3); // 索引数组
$array2 = array('name' => 'Tom', 'age' => 18); // 关联数组

1.2 Array access

Access array elements through array subscripts (index values ​​or associated keys), for example:

echo $array1[0]; // 输出 1
echo $array2['name']; // 输出 Tom

2. Modification of array elements

PHP provides a variety of methods for modifying array elements, which are introduced below.

2.1 Directly modify the element value

Use subscripts to directly modify the value of the array element, for example:

$array = array(1, 2, 3);
$array[0] = 4;
print_r($array); // 输出 Array ( [0] => 4 [1] => 2 [2] => 3 )

2.2 Use the array_splice function

array_splice function can Removes a range of elements from an array and replaces the removed elements with new elements. Syntax:

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 of the removed elements, $length represents the number of elements to be removed, and $replacement represents the replacement of the removed elements. new elements.

Example:

$array = array(1, 2, 3);
array_splice($array, 1, 1, 'a');
print_r($array); // 输出 Array ( [0] => 1 [1] => a [2] => 3 )

2.3 Using array_fill function

array_fill function can fill the specified number of elements into the array, syntax:

array_fill(int $start_index, int $num, mixed $value) : array

Among them, $start_index Indicates which subscript to start filling from, $num indicates the number of elements to be filled, and $value indicates the value to be filled.

Example:

$array = array(1, 2, 3);
$array = array_replace($array, array_fill(1, 1, 'a'));
print_r($array); // 输出 Array ( [0] => 1 [1] => a [2] => 3 )

2.4 Using the array_replace function

The array_replace function can replace the elements of one or more arrays with the elements of another array, syntax:

array_replace(array $array, array ...$arrays) : array

Among them, $array represents the original array to be replaced, and $arrays represents the new array used for replacement.

Example:

$array = array(1, 2, 3);
$array = array_replace($array, array(1 => 'a'));
print_r($array); // 输出 Array ( [0] => 1 [1] => a [2] => 3 )

3. Summary

Through the introduction of this article, we have learned about the basic concepts of PHP arrays and methods of modifying array elements. Arrays are one of the important data types in PHP. Mastering the basic operations of arrays is an essential part of web development.

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