Help understanding code...

I've just picked up a more advanced book on PHP and it has a lot of example code in it. I understand most of it but some things I'm seeing I don't understand. Like the following... code: ------------------------------------------------------------------------ -------- $couponcode = (! empty($_REQUEST['couponcode'])) ? $_REQUEST['couponcode'] : NULL; ------------------------------------------------------------------------ -------- I think this is saying: If the global variable couponcode is not empty, then the variable '$couponcode' is equal to "$_REQUEST['couponcode']" otherwise it gets a "NULL" value. What's throwing me is the use of the "!" and "?" and ":" If What I suspect is correct, I've never seen an if-then statement like this. If it is a replacement for an IF-Then statement then it's much cleaner and I'd like to use it. another one is: code: ------------------------------------------------------------------------ -------- IF (!strcmp($operator, '+')) { $result = $num1 + $num2 } ------------------------------------------------------------------------ -------- I've looked up strcmp() and know it's used to compair two strings. The $operator variable in the script that this was taken from is set to either "-", "+", "*" or "/". What I don't understand here is what the "!" in front of strcmp() means. Can anyone break down the code for me and explain the parts? thanks, Jeff