return needle not exist in haystack

Question

im using array_diff to check if ALL needles exist

    // my code
    $needle = array(' b', 'asb');
    $haystack = array('a','b','c','d','e');

    if (empty(array_diff($needle, $haystack))) {
        echo "The NEEDLE is in HAYSTACK";      
    }else {
      echo "The NEEDLE is NOT in HAYSTACK";
      // return 'asb'
    }

how do i return the needle is not in haystack? or is there any way to do this?

Answer 1

As you already have checked if all of the needles exist, you can just return a string using implode() to join the missing values into some form of list. I've extracted the array_diff() out so that you can re-use the value...

$needle = array('b', 'asb');
$haystack = array('a','b','c','d','e');

$difference = array_diff($needle, $haystack);
if (empty($difference)) {
    echo "The NEEDLE is in HAYSTACK";
}else {
    echo "The NEEDLE is NOT in HAYSTACK ";
    echo implode (",", $difference);
}

Note for the test data in this code, I have removed the space before the b in the $needle variable. As ' b' also doesn't exist in the $haystack.