comparing arrays

[nobertos]

Howdy ya'll,

I have two arrays that I want to compare. They contain email addresses:

$new_email_array
$old_email_array

// If only in new array, place in $array1
// If only in old array, place in $array2
// If in both arrays, place in $array3

what's a good way to do this cleanly?

so, for each value in $new_email_array i'll need to see if there is a match in $old_email_array. if there is, put it in $array3. for the values left over in $new_email_array, put them in $array1. for the values left over in $old_email_array, put them in $array2

Thanks alot!

[laserlight]

One idea is to loop though the new and old arrays.
For the first array, you can determine if an email is in both, or only in that current array.
In the next, if it isnt in both, it must be only in the current:

$array1 = array(); //for those only in new array
$array2 = array(); //for those only in old array
$array3 = array(); //for those in both arrays

//loop through the new array
foreach ($new_email_array as $email) {
	if (in_array($email, $old_email_array)) {
		$array3[] = $email; //in both arrays
	}
	else {
		$array1[] = $email; //only in new array
	}
}

//loop through old array
foreach ($old_email_array as $email) {
	if (!in_array($email, $array3)) {
		$array2[] = $email; //only in old array
	}
}

[Weedpacket]

There are also the [man]array_diff[/man] and [man]array_intersect[/man] functions.