A php custom function to get the file extension

/*
Get the file extension
Usage: GetFiletype($filename)
*/
function GetFiletype($Filename) {
if (substr_count($Filename, ".") == 0) { // Check whether there is a . number in the file name.
 return; // Return empty
} else if (substr($Filename, -1) == ".") { // Check if it ends with ., that is, no extension
 return; // Return empty
} else {
 $FileType = strrchr ($Filename, "."); // Cut from . number
 $FileType = substr($FileType, 1); // Remove . number
 return $FileType; // Return
}
}
$Filename = "index.php";
$Filename = GetFileType($Filename);
echo $Filename; // Print out php