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: 
It seems like you may have included the common.php file more than once. The second time it loaded would cause errors like that since the function is already loaded.

It is an odd error, but will probably seem logical once the problem is figured out. I would suggest looking at your includes, or switch them to include\_once. Maybe see what debug\_print\_backtrace() outputs before that function loads.
Sounds like you've got the common.php file included more than once. Do you use include(), require() or require\_once() for your includes?