Is Number Even

phpEvenCheck.php

<?
function isEven($g, $isIt = false) {
    $g--;
    $isIt = !$isIt;
    
    if($g <= 0) {
        if($isIt === TRUE) {
            echo "$ g is even!";
            return true;
        } elseif($isIt === FALSE) {
            echo "$ g is odd!";
            return false;
        }
    } elseif($g >= 1) {
        return isEven($g, $isIt);  //Recursion, because people will think I know what I'm doing.
    } 
}

isEven(5);
?>

Not sure how to fix this. It's pretty efficient on numbers < 10, but it's pretty rough on big numbers.

Very good approach. I'd suggest adding a seperate isEven function with $isOdd = false by default. Just for enterprise sake.