this is equivalent of in clause of MySql which checks if a value exists in multiple array values or not.

<?php // testfile.php
$something = array(1,2,5,6,3,9,6,12);
// in_array(<element to find out>, <in which array>)
if (in_array(5, $something)) {
    echo "found";
}
else
echo "back out";
?>