How to remove specified elements from an array in php

In PHP, if you need to remove specified elements from an array, there are many ways to do it. Some commonly used methods will be introduced below.

Method 1: Use the unset function

The unset function is used to destroy the specified variables, including elements in the array. You can use the unset function to remove elements at a specified position in the array. The sample code is as follows:

$arr = array(0 => 'a', 1 => 'b', 2 => 'c', 3 => 'd');
unset($arr[1]); // 删除索引为 1 的元素 b
print_r($arr); // 输出 Array ( [0] => a [2] => c [3] => d )

When deleting array elements through the unset function, you need to pay attention to the following points:

• If If the unset function is followed by an array variable, then the variable will be destroyed, not the array element;
• If the unset function is called without specifying the key name of the array element, the entire array will be destroyed.

Method 2: Use array_splice function

array_splice function can be used to delete a certain range of elements from an array, and move other elements in the array to corresponding positions to fill the deleted ones Elements. The function prototype is as follows:

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

Use the array_splice function to remove the element at the specified position of the array. This can be achieved by passing the position of the element to be removed in the array and the number of elements to be removed to the function:

$arr = array(0 => 'a', 1 => 'b', 2 => 'c', 3 => 'd');
array_splice($arr, 1, 1); // 从索引为 1 的位置开始移除 1 个元素
print_r($arr); // 输出 Array ( [0] => a [1] => c [2] => d )

When deleting array elements through the array_splice function, you need to pay attention to the following points:

• If the element to be replaced is not specified, the remaining elements in the array will fill the position of the deleted element. ;
• If the number of elements to be replaced is less than the number of elements to be deleted, the remaining elements to be deleted will not be deleted;
• If the number of elements to be replaced exceeds the number of elements to be deleted The number of elements, the remaining elements in the array will be moved to the right to ensure that there are no vacant positions.

Method 3: Use array_diff function

array_diff function can be used to compare the differences between two or more arrays and return a new array that is contained in the first array But elements that are not in other arrays. If we put the elements to be removed into an array separately, and then use the array_diff function to compare the original array and the array to be removed, the result will be the other elements except the elements to be removed. The sample code is as follows:

$arr = array(0 => 'a', 1 => 'b', 2 => 'c', 3 => 'd');
$remove = array('b');
$arr = array_diff($arr, $remove);
print_r($arr); // 输出 Array ( [0] => a [2] => c [3] => d )

When deleting array elements through the array_diff function, you need to pay attention to the following points:

• The elements to be removed must be placed in an array separately, otherwise it will affect the original array itself. Content;
• array_diff function will return a new array, the original array will not be affected;
• If there are elements with the same key name but different values ​​in the compared array, only the first element will is output to the result array.

Summary

The above is the method of deleting the elements at the specified position in the PHP array through the unset function, array_splice function and array_diff function. By choosing the appropriate method according to the actual situation, you can easily remove array elements.

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