array_intersect_ukey(): intersection between two arrays considering keys for checks through callback function

$new_array = array_intersect_ukey ($array1, $array2,....,my_function());

Example with two arrays

function my_function($a, $b)
{
    if ($a === $b) {
        return 0;
    }
    return ($a > $b)? 1:-1;
}

$first=array('One' =>'First','Two'=>'Second','Three'=>'Third','Fourth');
$second=array('1st'=> 'First','Two'=>'2nd','Three'=>'3rd','Fourth');

$result=array_intersect_ukey($first,$second,"my_function");
while (list ($key, $val) = each ($result)) {
echo "$key -> $val <br>";
}

Two -> Second 
Three -> Third 
0 -> Fourth 

Example 2: Using array_intersect_ukey() for Case-Insensitive Key Comparison

This example demonstrates how to use array_intersect_ukey() for case-insensitive key comparison, which is useful in scenarios where key case consistency isn't guaranteed.

function key_compare_func($key1, $key2) {
    return strcasecmp($key1, $key2);
}

$array1 = array('a' => 100, 'b' => 200, 'C' => 300);
$array2 = array('A' => 100, 'b' => 200, 'c' => 300);

$result = array_intersect_ukey($array1, $array2, 'key_compare_func');

print_r($result);

Output:

Array
(
    [a] => 100
    [b] => 200
    [C] => 300
)

Example 3: Filtering Arrays Based on Prefix in Keys

Filter two arrays to find common keys starting with a specific prefix, using a custom comparison function.

function prefix_compare($key1, $key2) {
    if (strpos($key1, 'pre_') === 0 && $key1 === $key2) {
        return 0;
    }
    return $key1 >= $key2 ? 1 : -1;
}

$array1 = array('pre_first' => 'apple', 'pre_second' => 'banana', 'post_third' => 'cherry');
$array2 = array('pre_first' => 'apple', 'second' => 'banana', 'third' => 'cherry');

$result = array_intersect_ukey($array1, $array2, 'prefix_compare');

print_r($result); 

Output:

Array
(
    [pre_first] => apple
)

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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