PHP startsWith and endsWith

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