How to find the intersection of arrays in php without using a function

php method to find the intersection of arrays without using a function: 1. Create a PHP sample file; 2. Define an empty array $result to save the intersection; 3. Loop through the first array $arr1 Each element $item1; 4. Loop through each element $item2 in the second array $arr2 again in the $arr1 loop; 5. Determine whether the two elements are equal, and if so, add it to the result array $result Medium; 6. After the loop ends, return the result array $result.

Operating system for this tutorial: Windows 10 system, php8.1.3 version, Dell G3 computer.

php can use a double loop to traverse the array, and then compare the array elements one by one to see if they are equal to achieve the intersection of the two arrays.

The specific method is as follows:

1. Define an empty array $result to save the intersection

2. Loop Loop through each element $item1

3. in the first array $arr1 and again loop through each element $item2

   in the second array $arr2 in the $arr1 loop.

4. Determine whether the two elements are equal. If they are equal, add it to the result array $result

5. After the loop ends, return the result array $result

Code example:

$arr1 = array(1, 2, 4, 6, 8);
$arr2 = array(3, 6, 8, 9, 10);
$result = array();
foreach ($arr1 as $item1) {
    foreach ($arr2 as $item2) {
        if ($item1 == $item2) {
            $result[] = $item1;
        }
    }
}
print_r($result);

Output:

Array
(
    [0] => 6
    [1] => 8
)

Note: Although this method can solve the intersection, the time complexity is O(n^ 2), it will be very slow when processing large-scale arrays, and is not recommended. A better solution is to use the PHP built-in function array_intersect().

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