Question: I received the following error:

```
[27-Apr-2009 10:26:06] PHP Fatal error:  Cannot redeclare alphanumeric() (previously declared in /home/iddoc/public_html/lib/common.php:6) in /home/iddoc/public_html/lib/common.php on line 8

```

Notice this:

```
/home/iddoc/public_html/lib/common.php:6) in 
/home/iddoc/public_html/lib/common.php on line 8

```

Here are the offending lines:

```
function alphanumeric($str) {
    return strtolower(preg_replace("/[^A-Za-z0-9]/",'',$str));
}

```

Prior to these lines there are only comments. There is no other declaration of that function anywhere else in that file or any other.

Strange, no?

Answer: 
Are you using `require`/`include` to reference the file? This is a common error when including a file twice. PHP doesn't know what to do if it sees two declarations, even if they're from an identical file.

Try using this:

```
include_once('lib/common.php');

```
Sounds like you've got the common.php file included more than once. Do you use include(), require() or require\_once() for your includes?