function startsWith($haystack, $needle) {

    // search backwards starting from haystack length characters from the end

    return $needle === "" || strrpos($haystack, $needle, -strlen($haystack)) !== FALSE;

}

function endsWith($haystack, $needle) {

    // search forward starting from end minus needle length characters

    return $needle === "" || (($temp = strlen($haystack) - strlen($needle)) >= 0 && strpos($haystack, $needle, $temp) !== FALSE);

}

startsWith("abcdef", "ab") -> true

startsWith("abcdef", "cd") -> false

startsWith("abcdef", "ef") -> false

startsWith("abcdef", "") -> true

startsWith("", "abcdef") -> false

endsWith("abcdef", "ab") -> false

endsWith("abcdef", "cd") -> false

endsWith("abcdef", "ef") -> true

endsWith("abcdef", "") -> true

endsWith("", "abcdef") -> false