Function to validate file extension ( PHP )

function validate_extension($file_name) {

$ext_array = array(".zip",".rar",".jpg",".jpeg",".gif",".bmp");
$extension = strtolower(strrchr($file_name,"."));
$ext_count = count($ext_array);


if (!$file_name) {
return false;
} else {
if (!$ext_array) {
return true;
} else {
foreach ($ext_array as $value) {
$first_char = substr($value,0,1);
if ($first_char <> ".") {
$extensions[] = ".".strtolower($value);
} else {
$extensions[] = strtolower($value);
}
}


foreach ($extensions as $value) {
if ($value == $extension) {
$valid_extension = "TRUE";
}
}


if ($valid_extension) {
return true;
} else {
return false;
}
}
}
}