How to remove keys from php array

In PHP, array is a very common data structure. We can store and manage a series of values ​​through arrays. However, in actual development, we may encounter situations where we need to remove a key-value pair in the array. So, how to remove key-value pairs from an array in PHP? In this article, we will detail how to remove keys from arrays in PHP.

1. Use the unset() function to remove a key-value pair from an array

In PHP, we can use the unset() function to remove a key-value pair from an array. The syntax of the unset() function is relatively simple, as follows:

unset($array['key']);

Among them, $array is the array to be operated on, and 'key' is The key to remove.

The following is a sample code:

// 声明一个包含键值对的数组
$array = array('name' => 'Tom', 'age' => 20, 'city' => 'Beijing');

// 移除数组中的 'city' 键值对
unset($array['city']);

// 输出移除后的数组
print_r($array);

The running results are as follows:

Array
(
    [name] => Tom
    [age] => 20
)

As can be seen from the output results, with the help of the unset() function, we successfully moved Except for the 'city' key-value pair in the array.

2. Use the array_diff_key() function to remove multiple array key-value pairs

If we need to remove multiple key-value pairs at one time, we can use the array_diff_key() function. This function is used to calculate the difference of an array, and the returned result is an array containing the difference elements. The specific syntax is as follows:

array_diff_key($array1, $array2, ...);

Among them, $array1, $array2, etc. are the arrays to be compared. Specifically, the function returns the key-value pairs in $array1 that are not in the subsequent array. The following is a sample code:

// 声明一个包含键值对的数组
$array1 = array('name' => 'Tom', 'age' => 20, 'city' => 'Beijing');

// 声明另一个数组，用于指定要移除的键
$array2 = array('city' => '');

// 移除 'city' 键值对
$result = array_diff_key($array1, $array2);

// 输出移除后的数组
print_r($result);

The running results are as follows:

Array
(
    [name] => Tom
    [age] => 20
)

As can be seen from the output results, the 'city' key value in $array1 was successfully removed using the array_diff_key() function right.

3. Use the array_splice() function to remove the array element at the specified position

In addition to directly removing a key-value pair, we can also use the array_splice() function to remove the array element at the specified position. This function is used to remove and replace a section of elements in an array. The specific usage is as follows:

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

where $array is the array to be operated on; $offset is the position of the first element to be removed/replaced. (Counting starts from 0); $length is the number of elements to be removed/replaced; $replacement is the element to be inserted. If you only want to remove elements at a certain position, set $length to 1 and $replacement to an empty array.

The following is a sample code:

// 声明一个包含多个元素的数组
$array = array('Tom', 'Bob', 'Lily', 'Kate', 'Jack');

// 移除第三个元素 'Lily'
array_splice($array, 2, 1);

// 输出移除后的数组
print_r($array);

The running results are as follows:

Array
(
    [0] => Tom
    [1] => Bob
    [2] => Kate
    [3] => Jack
)

As can be seen from the output results, the array_splice() function is used to successfully remove the 'Lily' element.

Summary

Arrays are a common data type in PHP. To remove a key-value pair in the array, you can use the unset() function; to remove multiple key-value pairs, You can use the array_diff_key() function; to remove elements at a specified position in the array, you can use the array_splice() function. The usage of these functions is relatively simple. Once mastered, arrays can be easily manipulated and development efficiency improved.

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