What a string ends with

I tried looking in the PHP docs but there are 50,000 String functions; how can I find out if a string ends with .gif, .png, .jpg, .bmp, or .jpg?

PHP Code:

---

// output array
$elements = count($dirs);
for ($i = 0; $i<$elements; $i++) {
    if (eregi("gif$|png$|jpg$|bmp$|jpg$|jpeg$", $dirs[$i])) {
        echo "<font color=\"#ff0000\">$dirs[$i] - Image File!</font><br>";
    } else {
        echo "$dirs[$i] - Not an image File<br>";
    }
} 


---

$ext = substr ("myfile.gif", -3);

$ext will be "gif"

Chris's way worked. I would've replied but I broke my Internet connection :(