The variable ' $return10 ' (for example) is a url, and I need to append ' &var2=example ' to the end. Like this:

```
 header( "Location: $return10&var2=example" );
 header ("Content-Length: 0");
  exit;

```

The challenge is not knowing if the url contained in ' $return10 ' will already have a query string.

Choice A) If I use ' &var2=example ' , then sometimes the final url will be ' ://example.com&var2=example ' , with no '?' to start the query string.

Choice B) If I use ' ?var2=example ' , then sometimes the final url will contain two "?"'s starting two different query strings??

Is there a third choice? How would you cover both possibilities using *"the correct code?"* Thank you.