Introduction to how to use the PHP array_intersect_ukey() function

What I want to introduce today is a very commonly used array function in PHP - array_intersect_ukey(). This function is mainly used to compare the key names in two or more arrays and return a new array that contains all key names that exist in all input arrays. The array_intersect_ukey() function mainly has the following characteristics:

1. Only compares the key names of the array, not the key values.
2. This function can compare two or more arrays at the same time.
3. Users can customize a function as a callback function to handle the comparison logic of key names.

Let’s take a look at the specific usage of this function.

How to use the function

Syntax: array_intersect_ukey (array $array1, array $array2 [, array $...], callable $key_compare_func): array

Parameter description:

array1, array2, ...: The arrays to be compared can be two or more arrays.

key_compare_func: User-defined callback function used to compare key names.

Return value: Returns an array containing all key names that exist in all input arrays.

Note:

1. The callback function receives two parameters, which are the key names to be compared.
2. The order of the key names in the array returned by this function may be different from the order in the input array.
3. This function is case-sensitive to the input array key name.
4. If there are keys with the same key name in the input array, the returned array will only contain the last key that appears.

Look at an example below:

Example 1:

$array1 = array('a' => 'php', 'b' => 'java', 'c' => 'python');

$array2 = array('a' => 'php', 'd' => 'ruby', 'e' => 'javascript');

function myfunction($key1, $key2)
{
    if ($key1 === $key2)
    {
        return 0;
    }
    else if ($key1 > $key2)
    {
        return 1;
    }
    else
    {
        return -1;
    }
}

print_r(array_intersect_ukey($array1, $array2, 'myfunction'));

Output result:

Array
(
    [a] => php
)

Explanation: In this example, we first define Create two arrays $array1 and $array2, and then define a callback function myfunction to compare the key names of the arrays. The function of this function is to return 0 when $key1 and $key2 are equal, to return 1 when $key1 is greater than $key2, and to return -1 when $key1 is less than $key2. Finally, we call the array_intersect_ukey() function, passing in the two arrays to be compared and the name of the callback function myfunction. The output result of the function is a new array whose key name only contains the key 'a' that exists in both input arrays, and the key value is 'php'.

Example 2:

$array1 = array('a' => 'php', 'B' => 'java', 'c' => 'python');

$array2 = array('a' => 'php', 'b' => 'ruby', 'e' => 'javascript');

print_r(array_intersect_ukey($array1, $array2));

Output result:

Array
(
    [a] => php
)

Explanation: In this example, we first define two arrays $array1 and $array2, pay attention to the array $array1 The middle key name 'B' is a capital letter. Then we call the array_intersect_ukey() function, which is case-sensitive by default, so it only returns the key 'a' that exists in both input arrays, and the key value is 'php'.

Conclusion

array_intersect_ukey() function is a very commonly used array function in PHP. It is mainly used to compare the key names of two or more arrays and return a new array. Contains key names that exist in all input arrays. At the same time, this function allows users to customize a callback function to handle the comparison logic of key names. In actual development, this function is often used in array comparison, duplication removal and other occasions, and is very convenient and practical.

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