Control cannot fall through from one case to another?
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LalalalaICantHearYouLalalalalala Outside of a single school exercise (Generate the complete lyrics for the 12 days of Christmas) I can't think of a single case where falling through was desired behavior. Seriously though, that's the exception which proves the rule. :-D
It is a truth universally acknowledged that a zombie in possession of brains must be in want of more brains. -- Pride and Prejudice and Zombies
dan neely wrote:
Outside of a single school exercise (Generate the complete lyrics for the 12 days of Christmas) I can't think of a single case where falling through was desired behavior.
It does happen occasionally. My current project has two switches where it was much clearer to add a "goto" rather than convoluted logic. The important thing, of course, is to comment it properly so everyone can see exactly what's being done, and why.
There are three kinds of people in the world - those who can count and those who can't...
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Computafreak wrote:
You just drop though each case. Why?
This is a state-machine with a selectable first state. If C# had a "computed goto" (as Fortran has) then the switch would not be necessary. :)
Luc Pattyn [Forum Guidelines] [My Articles]
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Luc Pattyn wrote:
This is a state-machine with a selectable first state. If C# had a "computed goto" (as Fortran has) then the switch would not be necessary.
Or do the state machine as a "while...switch..." loop, and set the initial state before entry. That's how I've always done it (and I do go back to the old Fortran days as well :)).
There are three kinds of people in the world - those who can count and those who can't...
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Why use a case at all, it seems pretty procedural to me. You want to execute a block of code in order, your condition isn't really needed since you always increment 'state', so your select case is useless.
I'm back. It depends on what
stateis equal to. As I have understood, thestate=1line is just an example of possible value which can takestate. Ifstatewould be fixed to 1 every time, 80% of could be removed, including the wholeswitchstatement. So the question to dec82: Isstate=1line just an example or is it actually present in the source code?Greetings - Jacek Gajek
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LalalalaICantHearYouLalalalalala Outside of a single school exercise (Generate the complete lyrics for the 12 days of Christmas) I can't think of a single case where falling through was desired behavior. Seriously though, that's the exception which proves the rule. :-D
It is a truth universally acknowledged that a zombie in possession of brains must be in want of more brains. -- Pride and Prejudice and Zombies
I agree that fall-through is evil, but there are still situations where you want to execute multiple cases; if not with goto, then some other keyword, at least the goto acts as a cry for help.
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I'm back. It depends on what
stateis equal to. As I have understood, thestate=1line is just an example of possible value which can takestate. Ifstatewould be fixed to 1 every time, 80% of could be removed, including the wholeswitchstatement. So the question to dec82: Isstate=1line just an example or is it actually present in the source code?Greetings - Jacek Gajek
Not necessarily. As Luc said earlier, this looks like a state machine implemented as a single switch block. As such, it may never exit! It could be accepting inputs from (say) Console.Readline and modifying
stateas a result. I've seen it done (by crap proceduraly oriented programmers) before.No trees were harmed in the sending of this message; however, a significant number of electrons were slightly inconvenienced. This message is made of fully recyclable Zeros and Ones
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This does not generate the same result. I set the i = 0. But consider that i is entered by the user. Console.WriteLine(0); Console.WriteLine(1); will not be the same, as in some cases only the case 1 must be executed. As I understand, the idea is to have the option to "start at any point", but continue from it. And I am not saying the solution used is a good one, but it is the easiest to convert a C++ code without really refactoring it.
Yeah. And then some poor sod (probably me with any luck) gets to maintain the ramshackle heap of spagetti. Do the job right. If you are converting C++ to C# then convert it to good C#. It may be you who has to "upgrade" it in six months time...
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hi I have these code . What could cause above error ? Thanks state=1 switch (state) { case 1: //do something goto case 2; case 2: //do something goto case 3; case 3: //do something goto case 4; ............ case 100: //do something }
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Not necessarily. As Luc said earlier, this looks like a state machine implemented as a single switch block. As such, it may never exit! It could be accepting inputs from (say) Console.Readline and modifying
stateas a result. I've seen it done (by crap proceduraly oriented programmers) before.No trees were harmed in the sending of this message; however, a significant number of electrons were slightly inconvenienced. This message is made of fully recyclable Zeros and Ones
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Kinda cool although unmaintainable a bit. I've posted him a link to my FSA stuff.
Greetings - Jacek Gajek
Jacek Gajek wrote:
Kinda cool although unmaintainable a bit.
Trust me, I'm not defending this code at all - I posted it to "Coding Horrors" - I like the understatement though! ;)
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There are times when a goto can really improve readability, rather than if...if..if..if... etc. Having said that, I don't think I've used one in a non-assembler language for twenty or so years.
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OriginalGriff wrote:
goto can really improve
Nope - never happenned in, yeah probably 15 years. It never even enters the thought processes as a tool to solve a problem, and I started programming VBA macros way back. If one of my juniors devs used a goto I'd attack him with a bar of soap, or super glue the g key to his forehead.
Never underestimate the power of human stupidity RAH
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Firstly, find the programmer who originally wrote this. Take him outside, and beat him senseless. It's pretty bad code as C++, and can't be directly translated into C# as the later enforces rules to prevent accidental mistakes (such as fall through of cases). Secondly, get out a pen and paper and do a flow diagram of some sort to work out how this spagetti works. Tidy the diagram up so it can be reliably implemented in any language. Re-code into C#. Not a quick job by any means, but it's the companies' (or whoevers') fault for allowing such rubbish to be produced in the first place!
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