array_intersect_key(): Intersection of two or more arrays considering keys only

$new_array = array_intersect_key ($array1, $array2,....);

Example with two arrays

$first=array('One' =>1,'Two'=>2,'Three'=>3,'Four'=>'Fourth');
$second=array('One'=>1,'Two'=>2,'Third'=>3);

$result1=array_intersect_key($first,$second);
while (list ($key, $val) = each ($result1)) {
echo "$key -> $val <br>";
}

One -> 1 
Two -> 2

Example with three arrays

$first=array('One' =>1,'Two'=>2,'Three'=>3,'Four'=>'Fourth');
$second=array('One'=>1,'Two'=>2,'Third'=>3);
$third=array('One'=>1);
$result1=array_intersect_key($first,$second,$third);
while (list ($key, $val) = each ($result1)) {
echo "$key -> $val <br>";
}

One -> 1

Example: Using Associative Arrays

$array1 = ['a' => 'apple', 'b' => 'banana', 'c' => 'cherry'];
$array2 = ['a' => 'avocado', 'b' => 'blueberry'];
$result = array_intersect_key($array1, $array2);
print_r($result);
// Output: Array ( [a] => apple [b] => banana )

Example: Filtering Array by Specific Keys

$array1 = ['name' => 'John', 'age' => 25, 'gender' => 'male', 'country' => 'USA'];
$keys_to_keep = ['name' => '', 'age' => ''];
$result = array_intersect_key($array1, $keys_to_keep);
print_r($result);
// Output: Array ( [name] => John [age] => 25 )

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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