Conditional (?) operator in PHP ?

Anon

I couldn't find any support for this in the manual. Does anyone know if PHP supports this operator?

For example, in C you can replace this:

if ( b < 0 )
a = -b;
else
a = b;

with this:

a ( b < 0 ) ? -b : b;

It looks to me that if PHP does support this, the "?" operator must take some sort of special treatment.

yelvington

That's called a ternary conditional operator, and it is documented on this page:

http://www.php.net/manual/en/html/language.expressions.html

It works as in C.

Anon

Thanks, I thought I saw that explained somewhere. I was looking in the wrong place in the Control Structures chapter in the if-else section.

I normally stay away from "clear as mud" code like this, prefering the simpler if-else construction. But I have a List Box with a lot of selections I am setting programmatically, and this will save a lot of typing.

I'll try this out and see how it goes.

yelvington

I think the PHP manual is pretty good overall, but it's weak in the area of crossindexing.

For those of us who cut our teeth on C,

$foo ? bar() : echo "sorry";

... is crystal-clear ... but it may look like Martian to everybody else.

kparker

Sorry, Steve, I not only know C, I teach it for the Univ. of Washington, but you'd definitely get marked down for that! The conditional operator is really only justified where you need a conditional expression:

   printf("%d run%s, %d hit%s, %d error%s",
      runs, runs==1? "":"s",
      hits, hits==1? "":"s",
      errors, errors==1? "":"s" );

Your example is really better handled by a plain old boring pedestrian if.

Anon

i'm a self-taught programmer, and i honestly hate to differ with someone who has legitmately 'paid their dues', so to speak, but if I may...

In a compiled program the whitespace, programming style, etc., isn't that big of a deal, since the actual executable strips and cleans it into it's finest form. The extra time is miniscule during compile-time, and is never a factor again. In PHP, on the other hand, the script is read at execution time, as written.

Taking this into consideration, the script you took exception with has a total of 28 characters, including the whitespace that makes it readable (which is important in any language, i'm sure you'll agree). The same script, written in standard, readable c-style format, and with the boring old if-else statement, tallies out to 43. This is a 65% larger snippet than the original. IMHO, less typing means less typos (meaning less bugs) as well, but that is opinion on my part.

As to the size, it doesn't seem like much of a difference until you think about how many times that script may be hit per minute on a large, active site, and how many such snippets there might be of such code. If compacting the logic in such statements reduces the overal size of the code by as little as a couple of percent, it is saving load time for all concerned.

Just my 2cp. Again, meant in all all respect to someone I understand is much more qualified than myself. If I am mistaken about this, I apologize and would appreciate another point-of-view.