Re: Help understanding code...

On Thu, 2003-09-25 at 12:47, Jeff McKeon wrote: > 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 "$_REQUEST['couponcode']" otherwise it > gets a > "NULL" value. > > What's throwing me is the use of the "!" and "?" and ":" Ternary operator, if the first expression evaluates to true then it returns the result of the second expression, otherwise it returns the result of the third expression. The ! is part of the first expression. > > If What I suspect is correct, I've never seen an if-then statement like > this. If it is a replacement for an IF-Then statement then it's much > cleaner and I'd like to use it. > > another one is: > > > code: > ------------------------------------------------------------------------ > -------- > IF (!strcmp($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? This is a short form for testing if the strings are equal. Rather than test if strcmp( x, y ) == 0 which requires a comparison, a single boolean operator is applied so that if 0 is returns the ! makes it true. This is generally a carry forward from C coding style, where I believe the ! style runs through the processor faster than the == style. HTH, Rob. -- .------------------------------------------------------------. | InterJinn Application Framework - http://www.interjinn.com | :------------------------------------------------------------: | An application and templating framework for PHP. Boasting | | a powerful, scalable system for accessing system services | | such as forms, properties, sessions, and caches. InterJinn | | also provides an extremely flexible architecture for | | creating re-usable components quickly and easily. | `------------------------------------------------------------'