<?php $string = "YOLOTest"; // bad, should print if (strpos($string, "YOLO") >= 0) { echo "YOLO!!!\n"; } // bad, should not print if (strpos($string, "SWAG") >= 0) { echo "SWAG!!!\n"; } // good, should print $res = strpos($string, "YOLO"); if ($res !== false && $res >= 0) { echo "YOLO!!!\n"; } // good, should not print $res = strpos($string, "SWAG"); if ($res !== false && $res >= 0) { echo "SWAG!!!\n"; }