How to delete key values ​​in an array in php

In PHP, deleting key values ​​in an array is a common operation. This operation can be used to remove unnecessary elements from a list or clear specific keys in an array. This article will introduce how to delete key values ​​​​in an array in PHP, and specifically explain the methods and techniques for deleting key values.

1. Use the unset() function to delete the key values ​​in the array

In PHP, you can use the unset() function to delete the key values ​​in the array. The syntax of the unset() function is as follows ：

unset($array[key]);

Where $key is the key value that needs to be deleted, $array is the name of the target array. For example, if we need to delete the key value "tom" in the following array:

$userList = array(
    "tom" => "male",
    "jerry" => "male",
    "lucy" => "female"
);

You can use the unset() function to complete the following operations:

unset($userList["tom"]);

After performing the above operations, " tom" key value will be deleted.

2. Use the array_diff_key() function to delete the key value in the array

In PHP, the array_diff_key() function can be used to find the difference between two or more arrays. Using this function, we can delete the specified key value in the array. You can pass the key value to be deleted and the target array as parameters, and a new array will be returned. The new array will not contain the key values ​​that need to be deleted.

For example, we still need to delete the "tom" key value in the $userList array above. The following code shows how to use the array_diff_key() function to perform this operation:

$userList = array(
    "tom" => "male",
    "jerry" => "male",
    "lucy" => "female"
);

$excludeList = array("tom" => "");

$newList = array_diff_key($userList, $excludeList);

print_r($newList);

In the above code, the $excludeList array defines the key values ​​that need to be deleted. The value can be any value, but the key name must be the key value that needs to be deleted. $newList is the new array obtained after executing array_diff_key(), in which the "tom" key value has been deleted. The output result is as follows:

Array ( 
    [jerry] => male 
    [lucy] => female 
)

3. Use the array_filter() function to delete the key value in the array

In PHP, the array_filter() function can be used to delete specified key values ​​​​in the array. This function returns a new array that has been filtered out of unwanted key values. The specific operations are as follows:

1. Use the array_filter() function to delete specific key values

In this case, we can create a delete function for the key value and then use the array_filter() function Filter out unnecessary key values. For example, we still need to delete the "tom" key value in the $userList array above. We can perform it in the following way:

$userList = array(
    "tom" => "male",
    "jerry" => "male",
    "lucy" => "female"
);

$newList = array_filter($userList, function ($key) {
    return ($key != "tom");
} ,ARRAY_FILTER_USE_KEY);

print_r($newList);

In the above code, we use a function that returns Boolean to delete the specified key value "tom". As mentioned before, the array_filter() function will return a new array $newList, in which the "tom" key value has been deleted:

Array (
   [jerry] => male
   [lucy] => female
)

2. Use the array_filter() function to delete the key value of the specified type

Use the array_filter() function to delete key values ​​of specified types or conditions in the array. For example, we need to filter out the key values ​​in the array that have a value of 0 or an empty string. The code below shows how to accomplish this:

$arr = array("1", "0", "2", "", "3");

$newArr = array_filter($arr, function ($value) {
    return !empty($value);
});

print_r($newArr);

In the above code, we use the empty() function to determine whether each value is empty. Then, we filter out the empty string using the array_filter() function. The output in this example is as follows: The 0s and empty strings in

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

$array have been removed.

4. Summary

This article discusses how to use the unset(), array_diff_key() and array_filter() functions to delete key values ​​​​in an array in PHP. In actual development, deleting key values ​​in an array is a common operation, and the above method also runs through all aspects of PHP development. By understanding these methods, we can easily operate elements in the array and improve development efficiency.

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