while (true) and for (; ; ) [modified]

[wizardzz]

What are your views on these? How often do you use or see them and in what cases? Just curious, it's a little debate with my project's Architect. To clarify, I don't mean the preference between the 2, but the use of such loops in production.

"Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming "Wow! What a Ride!" — Hunter S. Thompson

modified on Thursday, March 10, 2011 12:10 PM

[Henry Minute]

I have only used them, or their equivalent in other languages, for testing something. Never in production.

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[Nish Nishant]

Most compilers (managed and native) will generate the same output code for either construct. So it's more a matter of style and preference. Personally, the while(true) seems more readable and it's more obvious what it's meant to do.

Regards, Nish

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[wizardzz]

Ah, I'm going to modify my original post. I wasn't referring to the preference between the 2, but the use of infinite loops, especially if there is no breaks to exit the loop. I guess we have a crash-only design for some applications.

"Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming "Wow! What a Ride!" — Hunter S. Thompson

[Gary Wheeler]

Agreed.

Software Zen: delete this;

[Andy Brummer]

I think I've used while true a few times, mostly in either complicated parser code, or early on when I was learning threading. It can make sense when side effects and the loop exit criteria are so intertwined that you can't separate them easily to reduce the exit to a single boolean. However, that's a huge flag to refactor/write your code so things aren't so intertwined. If you don't have the time/flexibility to do that, then I'd choose while (true) over creating a convoluted mess of a loop body just to have a boolean value to exit on.

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[Nish Nishant]

Okay, I can't think of why anyone'd have a while-true (or otherwise infinite) loop that does not have any normal exit conditions. Although you could break out via an exception it just does not seem very clean to me.

Regards, Nish

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New article available: Resetting a View Model in WPF MVVM applications without code-behind in the view My technology blog: voidnish.wordpress.com

[Gary Wheeler]

They are useful constructs, depending upon the algorithm. "Production" or not doesn't enter into it. Proscribing certain programming constructs in 'production' code is a naive method of quality enforcement.

Software Zen: delete this;

[Slacker007]

All my applications run to infinity and beyond. ;)

[Luc Pattyn]

I avoid while(true) and while(TRUE). I use for(;;) often; in C it is the one construct that gets accepted by all compilers without generating warnings; testing a constant expression in an if or while tends to cause a warning on a lot of compilers. Such "infinite loops" (nothing is infinite AFAIK) are fine: - when they are intended to loop forever (a lot of embedded systems don't care about orderly shutdown); - or when the loop exit condition isn't the first or last thing in the loop. :)

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[Rama Krishna Vavilala]

for(;;) is the more common one. I found the first mention of it being somewhat of a standard in the Stourstrup's book - "The C++ Programming language".

[Joan M]

Typical in PLC programs and machine programming in which you need to create an infinite loop that controls all the behavior of the machine itself. Most of them though have it implicitly working without the programmer knowledge... Also it was sometimes used in oooooold programs in which the sequential programming (that thing that existed before OOP)... It can also be used for testing... It can also be used to crash a computer ==> while(true){a=a+0.00000000001;} // patience... it will explode sometime... well, this can also be used to cook eggs direct on the computer's box... and after that (and even I know you did not asked for that...) I prefer "while(true)" it seems more clear to me...

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[Hans Dietrich]

I agree. There must be a mechanism to exit such loops cleanly.

Best wishes, Hans

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[Hans Dietrich Software]

[Ennis Ray Lynch Jr]

LABEL: ..code GOTO LABEL Much nicer.

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[Chris Meech]

Would you be talking about an Alderson Loop[^]. :) While the Wiki article is not a definitive reference, it seems that the practical use of infinite loops are minimal. I'd recommend to avoid them entirely. :)

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[RugbyLeague]

I use them although not often. I also often add an empty IDisposable to classes in C# because I like to wrap things in "using" :~

[Dave Parker]

Real men use "goto" :p

[Luc Pattyn]

break, return, yield, goto, throw, Application.Exit(), longjmp(), ... can all be justified given the right circumstances. :)

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[bob16972]

They are both handy from time to time (expression parsing and times when you don't know how many iterations will be needed). I personally prefer while(TRUE) so as not confuse any VB programmer that comes across my code.

[Nemanja Trifunovic]

wizardzz wrote:

What are your views on these?

Infinite tail-recursion is much nicer.

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