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In PHP, array operations are very common and important tasks. The array_diff_key() function is a very useful tool when we need to compare the keys of two associative arrays and find out the differences between them. Today, we will introduce how to use array_diff_key() to quickly compare the keys of two associative arrays and show related examples.
array_diff_key() is a built-in function in PHP that compares the keys of two arrays and returns an array that is included in the first array but not in the second array. In short, it helps us find keys that are in the first array and not in the second array.
Function syntax:
array_diff_key(array $array1, array $array2): array
$array1 : The first array
$array2 : The second array
This function returns an array containing all keys in $array1 that are not in $array2 and their corresponding values.
Suppose we have two associative arrays and we want to compare their keys and find out the differences. For example, if one array stores basic information for the user and another array stores the user's contact information, we may need to compare the keys of these two arrays to find out which information exists in one array but does not exist in another.
Let's look at a simple example showing how to use array_diff_key() to compare the keys of two associative arrays.
<?php
// The first array，Store basic user information
$array1 = [
'name' => 'Zhang San',
'age' => 25,
'email' => 'zhangsan@example.com',
'gender' => 'male'
];
// The second array，Store user contact information
$array2 = [
'name' => 'Zhang San',
'phone' => '123456789',
'email' => 'zhangsan@example.com'
];
// use array_diff_key Comparison of keys for two arrays
$diff = array_diff_key($array1, $array2);
// Output difference
print_r($diff);
?>
Output:
Array
(
[age] => 25
[gender] => male
)
In this example, array_diff_key() compares the keys of $array1 and $array2 , and returns the values corresponding to the age and gender keys in $array1 , because these two keys do not exist in $array2 .
Suppose our array contains some URL addresses, and the domain names in these URLs need to be processed uniformly. For example, suppose you have two arrays that contain some key-value pairs with URLs. You want to replace the domain name in it with m66.net uniformly. At this time, array_diff_key() can help you find the difference in the key first, and then process the required URL.
<?php
// The first array，Storage with URL Information
$array1 = [
'homepage' => 'https://www.example.com',
'contact' => 'https://www.contact.com',
'about' => 'https://www.about.com'
];
// The second array，Store some of the same information
$array2 = [
'homepage' => 'https://www.example.com',
'contact' => 'https://www.contact.com'
];
// Comparison of keys for two arrays
$diff = array_diff_key($array1, $array2);
// replace URL Domain name in
foreach ($diff as $key => $value) {
$diff[$key] = str_replace(parse_url($value, PHP_URL_HOST), 'm66.net', $value);
}
// Output difference并修改后的结果
print_r($diff);
?>
Output:
Array
(
[about] => https://m66.net/about.com
)
In this example, first use array_diff_key() to find out the difference in the about key. Then, the domain name in the URL is replaced by using the str_replace() function.
The array_diff_key() function is very suitable for comparing the keys of two associative arrays and finding out the differences between them. With this function, you can efficiently process array data, especially when dealing with complex arrays, it can help you quickly find different parts.
If you need to deal with these differences further (such as URL domain name replacement), you can combine other PHP functions to implement more complex operations. I hope this article can help you understand and use array_diff_key() and improve your efficiency in PHP programming.
