How to delete two-dimensional array elements in php

In PHP, array is a very common data type. During development, we often need to add, update, or delete array elements. Among them, deleting array elements is one of the common operations. However, you may encounter some problems when deleting elements from a two-dimensional array. This article will introduce different ways to delete two-dimensional array elements in PHP.

1. Use the unset() function to delete two-dimensional array elements

In PHP, the unset() function can be used to delete variables or array elements. For two-dimensional arrays, we can use the unset() function to delete specified elements. Here is a sample code:

<?php // 定义一个二维数组
$users = array(
    array(&#39;name&#39; => 'Tom',  'age' => 12),
    array('name' => 'Jack', 'age' => 20),
    array('name' => 'John', 'age' => 30)
);

// 删除 $users[1] 元素
unset($users[1]);

// 输出删除后的数组
print_r($users);   // 输出：Array ( [0] => Array ( [name] => Tom [age] => 12 ) [2] => Array ( [name] => John [age] => 30 ) )

?>

In the above code, we use unset($users[1]) to delete the second element in the $users array. It should be noted that the unset() function does not reorder the array, so the original key values ​​will still be retained in the deleted array. In this example, the deleted array still contains the original keys 0 and 2.

2. Use the array_splice() function to delete two-dimensional array elements

The array_splice() function in PHP can be used to delete elements from an array and return the deleted elements. Its syntax is as follows:

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

Among them, $input is the array to be operated on, $offset is the starting position of the element to be deleted, $length is the number of elements to be deleted, and $replacement is optional. The inserted element. The return value is an array of deleted elements. The following is an example of using array_splice() function to delete two-dimensional array elements:

<?php // 定义一个二维数组
$users = array(
    array(&#39;name&#39; => 'Tom',  'age' => 12),
    array('name' => 'Jack', 'age' => 20),
    array('name' => 'John', 'age' => 30)
);

// 删除 $users[1] 元素
$deleted_elements = array_splice($users, 1, 1);

// 输出删除后的数组和被删除的元素
print_r($users);              // 输出：Array ( [0] => Array ( [name] => Tom [age] => 12 ) [1] => Array ( [name] => John [age] => 30 ) )
print_r($deleted_elements);   // 输出：Array ( [0] => Array ( [name] => Jack [age] => 20 ) )

?>

In the above example, we use array_splice($users, 1, 1) to delete the second element in the $users array element. The function return value is the deleted element array. It should be noted that the array_splice() function reorders the array, so the deleted array does not contain the deleted key values.

3. Use the array_filter() function to delete two-dimensional array elements

The array_filter() function in PHP can be used to filter elements in an array. We can use this function to delete elements in a two-dimensional array. Here is a sample code:

<?php // 定义一个二维数组
$users = array(
    array(&#39;name&#39; => 'Tom',  'age' => 12),
    array('name' => 'Jack', 'age' => 20),
    array('name' => 'John', 'age' => 30)
);

// 删除 $users[1] 元素
$users = array_filter($users, function($k) { return ($k != 1); }, ARRAY_FILTER_USE_KEY);

// 输出删除后的数组
print_r($users);       // 输出：Array ( [0] => Array ( [name] => Tom [age] => 12 ) [2] => Array ( [name] => John [age] => 30 ) )

?>

In the above example, we used the array_filter() function to delete the second element in the $users array. We pass the callback function as the second parameter to the array_filter() function. The callback function is used to determine whether the key is to be retained. The ARRAY_FILTER_USE_KEY flag is used to tell the callback function that it requires a key name instead of a key value as a parameter.

Summary

In PHP, we can use the unset() function, array_splice() function or array_filter() function to delete elements in a two-dimensional array. Specified elements can be easily removed using the unet() function and array_splice() function, while elements can be removed based on specified conditions using the array_filter() function. Which method you choose depends on your specific development needs.

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