Question: about ? and :

[PureEvil]

I've pretty much learned all of my PHP from a few books I'ver purchased and of course this kick ass web site.

The question is this. I keep seeing code like the following
[code]$row_color = ($Rcount % 2) ? $Talt_color1 : $Talt_color2;[/code]

What does the ? and the : mean in that string? I've been unable to find these in my books.

Thanks in advance.

[spires]

I'm in the same boat.

every book or CD that i have used dosen't explain ? or :

Can anyone explin exactly what this line of code does?
[code]
foreach ($items as $item) {
$contents[$item] = (isset($contents[$item])) ? $contents[$item] + 1 : 1;
}
[/code]

Cheers

[ChaosXero]

It's an if/else statement I believe.

(if) ? true : false (but I might be wrong on the order.)

[ChaosXero]

Aha! From the manual:
[code]Left associativity means that the expression is evaluated from left to right, right associativity means the opposite. Example 15-1. Associativity

<?php
$a = 3 * 3 % 5; // (3 * 3) % 5 = 4
$a = true ? 0 : true ? 1 : 2; // (true ? 0 : true) ? 1 : 2 = 2

$a = 1;
$b = 2;
$a = $b += 3; // $a = ($b += 3) -> $a = 5, $b = 5
?> 

Use parentheses to increase readability of the code.

[/code]

http://us2.php.net/manual/en/language.operators.php

[spires]

cheers,

I'll try and get my head around it.
;D

[PureEvil]

[quote author=ChaosXero link=topic=101251.msg400473#msg400473 date=1153408568]
It's an if/else statement I believe.

(if) ? true : false (but I might be wrong on the order.)
[/quote]

Ok I think I'm getting it maybe.

Basically in a nutshell your saying that if something is true or false do whats true or false.

Example:
[code]$i=1;
$Var1 = "i is 1";
$Var2 = "i is not 1";
$Var3 = ( $i == 1 ) ? $Var1 : $Var2;
echo("$Var3"); // should produce "i is 1"
[/code]

Is that correct?

[ChaosXero]

I'm not sure really.  I'm at work, so I cant try, but if someone could try/confirm this, I'd be interested to know.

[PureEvil]

[quote author=ChaosXero link=topic=101251.msg400574#msg400574 date=1153414234]
I'm not sure really.  I'm at work, so I cant try, but if someone could try/confirm this, I'd be interested to know.
[/quote]

Seems to work... That is awesome and will come in extra handy. Honest to god I have four php books I pretty much live in while I'm trying to write my scripts, and not one of them said anything about this. Very handy...

[scliburn]

yes you are correct, it simplifies an if/else alot like the switch statement

$thefunc = ((isset($var)) && ($var != '')) ? _function ( $var, $var2 ) : $content = 'No Word Entered<br /><br />';

you can use it call and pass vars through a function and then $thefunc could have the value returned from your functions.. just an example

[effigy]

It can also be shortened to:

[code]echo $i == 1 ? $Var1 : $Var2;[/code]

[ryanlwh]

it's a "ternary" operator that's adopted from C like languages. It's really sad to see php books don't cover this operator much. This is a really handy operator. You can even use it in a concatenation.

[code]echo 'This is a '.( $good ? 'good' : 'bad'). 'book';[/code]