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

Your assumptions are correct. It's called a ternary operator and it is
a substitution or the if-else statements. I try not to overuse it since
I don't think it's as readable as the block if statement. But for
things not assigning a value to a variable, I think it's better than
the block statement since you're more interested in the variable
declaration than the condition of it's value.


On Thursday, September 25, 2003, at 12:47 PM, 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 "$_REQUEST['couponcode']" otherwise it gets a
> "NULL" value.
>
> What's throwing me is the use of the "!" and "?" and ":"
>
> If What I suspect is correct, I've never seen an if-then statement like
> this. If it is a replacement for an IF-Then statement then it's much
> cleaner and I'd like to use it.
>
> another one is:
>
>
> code:
> -----------------------------------------------------------------------
> -
> --------
> IF (!strcmp($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
>
> --
> PHP General Mailing List (http://www.php.net/)
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>
>
--
Brent Baisley
Systems Architect
Landover Associates, Inc.
Search & Advisory Services for Advanced Technology Environments
p: 212.759.6400/800.759.0577

Hi,
It's a "C Like Syntax"

(condition)?true:false;

is like :

if (condition) true
else false

regards.
P.E. Baroiller

"Jeff McKeon" <jmckeon@telaurus.com> a écrit dans le message de
news:B3F5C378E4B6034CA27B15C99E9133CE63EAD4@exch01 tc07927.telaurus.net...
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