How to delete array based on key in php

In PHP, we often need to perform operations such as adding, deleting, modifying, and checking arrays. Among them, deletion operation is a common type of array operation, because in actual development we will encounter many situations where certain elements need to be deleted. This article mainly introduces how to delete elements in an array based on key.

1. unset function

PHP provides a function unset(), which can be used to delete specified elements in the array. Its syntax is as follows:

unset($array[key]);

Among them, $array is the array of elements to be deleted, and key is the key name of the element to be deleted.

The sample code is as follows:

// 创建一个关联数组
$arr = array(
    'name' => 'Tom',
    'age' => 18,
    'gender' => 'male'
);

// 删除元素 age
unset($arr['age']);

// 输出结果
print_r($arr);

The output result is as follows:

Array
(
    [name] => Tom
    [gender] => male
)

As can be seen from the output result, the element age has been successfully deleted.

2. array_splice function

In addition to using the unset() function, you can also use another built-in function in PHP array_splice() Remove elements from an array. This function can delete one or more consecutive elements in the array and return the deleted element array. Its syntax is as follows:

array_splice($array, $offset, $length);

Among them, $array is the array of elements to be deleted, $offset is the starting position of the element to be deleted, $ length is the number of elements to be deleted.

The sample code is as follows:

// 创建一个索引数组
$arr = array(0, 1, 2, 3, 4, 5);

// 删除索引为 2、3、4 的连续 3 个元素
$deleted = array_splice($arr, 2, 3);

// 输出结果
print_r($arr);
print_r($deleted);

The output result is as follows:

Array
(
    [0] => 0
    [1] => 1
    [5] => 5
)
Array
(
    [0] => 2
    [1] => 3
    [2] => 4
)

As can be seen from the output result, elements 2, 3, and 4 have been successfully deleted and stored in $deleted variable.

It should be noted that the array_splice() function will change the structure of the original array, so it needs to be used with caution.

3. array_diff_key function

Another common approach is to use the array_diff_key() function, which can compare the key names of two arrays and return the key name difference set. Through this function, we can easily delete elements corresponding to one or more key names.

The sample code is as follows:

// 创建一个关联数组
$arr = array(
    'name' => 'Tom',
    'age' => 18,
    'gender' => 'male'
);

// 要删除的键名数组
$keys = array('age', 'gender');

// 使用 array_diff_key 函数删除键名对应的元素
$result = array_diff_key($arr, array_flip($keys));

// 输出结果
print_r($result);

The output result is as follows:

Array
(
    [name] => Tom
)

As can be seen from the output result, the elements age and gender has been successfully deleted.

It should be noted that the array_diff_key() function returns a difference array. The original array will not be changed, so the return result needs to be saved in a new array.

4. Conclusion

In PHP, we can use a variety of methods to delete elements in an array, including the unset() function and array_splice() Functions are the two most commonly used methods. In addition, using the array_diff_key() function is also a more flexible method, which can delete elements in the array based on the key name.

It should be noted that when performing array operations, be sure not to destroy the structure of the array to avoid unexpected situations.

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