Could someone explain to me what this does?

[Quzar]

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	conf.fullscreen=conf.fullscreen ? 0 : 1;

i think it says, if fullscreen is 0 then make it 1 and visa versa, but i have never seen this sort of operation before.

[Rand Linden]

You are correct.

Although, it would probably be clearer to use:

conf.fullscreen = (1-conf.fullscreen);

Of course, that assumes that the value is either 0 or 1 always, but you get the idea... there's a bunch of ways to write the toggle that are far easier to read -- many will break depending on the compiler and all sorts of other issues...

The construct you quoted is actually quite useful in all sorts of cases -- whether or not it's "cleaner" or "faster" to use it to toggle booleans will depend on the compiler and all sorts of other stuff.

Rand.

edit: I've usually heard of it as a "trinary" operation -- think "binary", but using tri... Do a google for "trinary c c++ language" and you'll find it easily.

[Ex-Cyber]

It's also commonly spelled "ternary", for reasons that are clearly beyond my feeble grasp of linguistics. It's also sometimes called the "conditional operator".

[ATani]

You are correct.

Although, it would probably be clearer to use:

conf.fullscreen = (1-conf.fullscreen);

Another common construct for this is:
conf.fullscreen = !conf.fullscreen;

Which depending on your compiler will do the same thing..

Mike

[Quzar]

Now, does anyone know which of these is the best solution? That is, not for readability, but for speed.

[Rand Linden]

Another common construct for this is:
conf.fullscreen = !conf.fullscreen;

Which depending on your compiler will do the same thing..

Mike

Yes, that's correct also...

I was trying to avoid all the boolean vs. binary logic issues that arise with compilers and optimizations and all sorts of other crap...

... but feel free to expound upon all the inane nuances if you want!

quzar: Chances are very (very) high that a toggle operation isn't where you need to be worrying about speed optimizations.

Rand.

edit: I've also heard of that type of construct as a "choice" operator, but that terminology is a bit misleading... but I'm adding this just incase you can't find sufficient search results using all the other stuff.

[Quzar]

ok, thanks for your help =).

one last question. Are there any other ternary/trinary operators? many of the references i have found simply say "the ternary operator".

[BlackAura]

Just the one.

[nymus]

my suggestion is that you should use a boolean variable for "conf.fullscreen" instead of an int; most compilers can optimize booleans. saying 1 or 0 might be ambigous. use "true" and "false" instead. I agree that "comp.fullscreen=!comp.fullscreen" is the best choice.

If you are using c++, I would also seriously recommend wrapping such confusing or ambigous constructs in an inline function. Rand gave it a cool name (toggle) so If I were you, I would write a function

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inline void toggle(bool *const boolean) { *boolean = !(*boolean); }

you can then call the function like this

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toggle(&conf.fullscreen);

This is good because the code will not incur overhead, it will be as if you had written the code verbatim and it will be clearer beacuse instead of seeing the confusing "conf.fullscreen=!conf.fullscreen" everywhere in your code, you'll see "toggle(&conf.fullscreen) and you will be able to use a different algorithm by editing only one piece of code and you can use the toggle for other boolean variables too!

[Rand Linden]

Using a bool is clearly preferable if you can only have logical choices -- and, accordingly, using the bang operator makes sense.

Also, you can pass the address as a reference, and then avoid the "&" entirely -- put it in the function prototype and forget about it.

Of course, you don't really need to pass it as a pointer anyway, but that's a whole seperate issue.

Rand.

[Quzar]

Using a bool is clearly preferable if you can only have logical choices -- and, accordingly, using the bang operator makes sense.

What's a bang operator?

[mogorman]

! < bang

[Quzar]

ah, ok.

[nymus]

Also, you can pass the address as a reference, and then avoid the "&" entirely -- put it in the function prototype and forget about it.
Rand.

I passed it as a pointer to follow recommended convention of informing explicitly that the variable is being modified but in this case one could safely assume, I guess.

[Rand Linden]

Here's a couple more tips to help you out:

Tip 1: The more frequently you ask questions that could (and SHOULD) have been answered by doing a search, the less frequently people will help you out.

Tip 2: When you post fewer lines of text than your signature, consider not posting at all.

Rand.

[Rand Linden]

I passed it as a pointer to follow recommended convention of informing explicitly that the variable is being modified but in this case one could safely assume, I guess.

The const confuses things though, and hence the suggestion to avoid the pointer entirely.

Either way, do what works for you.

Rand.

edit: And again, that's why I suggested avoiding passing a pointer at all -- especially for a simple boolean toggle... although the inline tip is a good one!

[Quzar]

Here's a couple more tips to help you out:

Tip 1: The more frequently you ask questions that could (and SHOULD) have been answered by doing a search, the less frequently people will help you out.

Tip 2: When you post fewer lines of text than your signature, consider not posting at all.

Rand.

sorry, i tried doing a search but without knowing what the '?' operator was called it was hard to just look for "? C++". Then my second question about more ternary operators was asked because i did a search after finding out what it was called and some places said that it was "a ternary operator" and others said "the ternary operator" and i couldnt find a proper answer. The last question was frivilous i admit, but didnt cause any trouble.

[Rand Linden]

quzar, I raised the issue with repsect to the last post you made, not the earlier ones.

http://www.google.com -- Search for "bang operator" -- on the first page, without even going to a link, there are three (or more) references that show what the bang operator is.

Again, in the future, consider searching first if you're genuinely interested in programming.

Rand.