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

[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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[TheGreatAndPowerfulOz]

RugbyLeague wrote:

IDisposable to classes in C#

That's silly. It serves no purpose, except obfuscation and misrepresentation, if you don't implement the IDisposable!

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[Ian Shlasko]

Checking my production system, it looks like I've used while (true) in six places... #1: Background thread that continuously monitors a Named Pipe #2: Background thread that periodically checks for application updates #3: Background thread that uploads trades as they're queued #4: Background thread that watches for incoming messages from the server #5: Background thread that sends heartbeats to the server #6: Background thread that handles message routing ON the server Basically, all of them are intended to run throughout the life of the application... They all have a sleep or a wait handle, but otherwise just loop continuously... It's a useful construct. Yes, I suppose I could add a global "Shutting down" condition, but it just hasn't been necessary. They catch the thread abort, clean up in the 'finally', and are designed so as not to damage anything external if the shutdown interrupts them at any point.

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[Chris Maunder]

Beat me to it!

cheers, Chris Maunder The Code Project | Co-founder Microsoft C++ MVP

[Chris Losinger]

i like em just fine, in things like state machines, where the endpoint is unknown. do{...}while(ok) is ok, too.

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[AspDotNetDev]

I like to consolidate:

for (; ; MessageBox.Show("Hello")) ;

:rolleyes: And here's the best I could do in VB.net:

For i As Integer = 0 To 0 Step 0
Next

Like somebody else mentioned, they may have their uses in background threads.

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[Christopher Duncan]

Nishant Sivakumar wrote:

what it's meant to do.

Hang the app with an endless loop? :)

Christopher Duncan Author of The Career Programmer Watch Bad Programmer! - Premieres May, 2011

[Nish Nishant]

Christopher Duncan wrote:

Hang the app with an endless loop?

Only on a single core machine :-D

Regards, Nish

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[Christopher Duncan]

:laugh:

Christopher Duncan Author of The Career Programmer Watch Bad Programmer! - Premieres May, 2011

[Jun Du]

I don't find many situations where I must use either. Something like while(!done) gives you a control over whether and when to exit, normal or abnormal.

Best, Jun

[Mike Hankey]

I use the while(true) consistently...in embedded apps. (AVR)

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[CPallini]

Not always. In C applications, for instance, you may know in the middle of the loop that you've to exit and while you may skip the following statements with an if and then use the condition, I prefer an immediate break.

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