goto statement

[Lost User]

You have just gained a level. Instead of blindly following some master wizard's rules, you now have begun to make your own. Before you know it you will zap your opponents with pointy pointers and even manage memory yourself. I actually prefer working with people who occasionally contemplate to break the rules instead of reciting them. :)

Sent from my BatComputer via HAL 9000 and M5

[Lost User]

That's fun too, but no - I mean the thing where they place the loops in a function and the goto turns into a return, and then they pretend that isn't really the same thing.

[Gary R Wheeler]

I've made my living programming since 1980. I've written millions of lines of code in everything from C#, C++, C, to several assembly languages. I've been writing C# since 2008. I've never needed to use goto. I've been writing C++ since 2000. I've never needed to use goto. My C code, written from 1990 to around 2002, used goto solely for exception handling. The Microsoft and Watcom C compilers at the time didn't support exceptions in a robust fashion.

Tarek Elqusi wrote:

Troubles are based on the programmer who is misusing it

While that statement is true, the converse is not. I've never found a case in modern times where goto was necessary. There is always a structured alternative. If a programmer is good enough, they will not need goto.

Software Zen: delete this;

[Kornfeld Eliyahu Peter]

You mean you are 'grown up'! Can't believe that... :laugh: But as for the rest I agree with you - don't break rules just for breaking them...

I'm not questioning your powers of observation; I'm merely remarking upon the paradox of asking a masked man who he is (V).

[Gary R Wheeler]

OriginalGriff wrote:

it needs a careful look at the whole of what is occurring and frequently a change of algorithm as well as hand-tuning of the code

I've done some minor bits of optimization on occasion. I've never needed goto as part of any hand-tuning. Algorithm improvements and refactoring are generally the way to go for me.

Software Zen: delete this;

[OriginalGriff]

Good grief no! I'm just old.

The only instant messaging I do involves my middle finger. English doesn't borrow from other languages. English follows other languages down dark alleys, knocks them over and goes through their pockets for loose grammar.

[altomaltes]

Ahh... This is one of my favourite subjects. I think we went to the total unbalance of the overpopulation of gotos of BASIC to the total unbalance of goto starvation on structured languajes. A goto is perfect for some weird situations. Imagine your fiancee calls you at work, because you've won severals milions on LOTO. May be your exit from work will be no too structured, and so must be. In others words goto deals well with some fatal error situatios, a glance at linux kernel code shows this. What? I'm getting seriuous. goto minibar.

[Pablo Aliskevicius]

If you don't think that GOTO is an interesting topic of conversation, try the Duff device. http://www.lysator.liu.se/c/duffs-device.html[^]

Pablo. "Accident: An inevitable occurrence due to the action of immutable natural laws." (Ambrose Bierce, circa 1899). "You are to act in the light of experience as guided by intelligence" (Rex Stout, "In the Best Families", 1950).

[PIEBALDconsult]

:thumbsup: I'd never seen that before. Awesome.

[PIEBALDconsult]

altomaltes wrote:

your exit from work will be no too structured

That's an interrupt.

[PIEBALDconsult]

It's fine when it's the only tool in the box (very old BASIC, DCL, DOS batch files, etc.), but I've never needed it in languages that support structured programming.

[Tarek Elqusi]

Could this be written by C# ?

[Forogar]

After using FORTRAN for far too long (up to Fortran-77) with it's use of GOTO and, even more obfuscating, computed gotos, I started using C. However, I was self-taught and was therefore never was taught by anybody that there was a GOTO in the language! I used C for several years, then C++ and now I am firmly in the C# camp. I personally have never used GOTO in any of that code and was shocked one day to find a GOTO residing in someone else's code I had to fix. It was a revelation as big as finding out that one is allowed to use guns during a penalty kick-off. I didn't even know the syntax existed! The whole point of my argument is that I never felt the need for a GOTO at any time, ever - so I didn't miss it. I didn't make artificial constructs to get around using GOTO; I didn't deliberately re-write my code to avoid using one; it just came about naturally that I didn't ever need one. Having said that, I am sure that GOTO may be useful in some real-time code somewhere for performance reasons. My real bug-bear is with multiple RETURNs. I do actually go out of my way to avoid them and re-write them out of existence wherever I find them. I have not yet found any instance where multiple RETURNs from a method has been necessary. I miss allowing the drop through of CASE statements in a switch that has been removed in C#, forcing me to put BREAK at the end of each part and leading me to repeat code unnecessarily now and then so I am not always in favour of compiler/syntax restrictions in a language but I wish multiple RETURNs had been proscribed in the same way.

- I would love to change the world, but they won’t give me the source code.

[OriginalGriff]

I disagree to an extent with you about multiple returns: I'd rather see a method with validations at the top, each with it's own error report and a return than some "faffing about" code to avoid it. I just think it makes the code look cleaner.

The only instant messaging I do involves my middle finger. English doesn't borrow from other languages. English follows other languages down dark alleys, knocks them over and goes through their pockets for loose grammar.

[Forogar]

I always structure things to do validation at the top a bit like:

private bool SomeMethod(string someStingArg, int anIntArg)
{
bool workedOK = false;
if (IsValidForThisFunction(somString) && IsAlsoValid(anIntArg))
{
// Do stuff here...
workedOK = true;
}
return workedOK;
}

...or, if individual validations are necessary...

private bool SomeMethod(string someStingArg, int anIntArg)
{
bool workedOK = false;
if (IsValidForThisFunction(somString))
{
if (IsAlsoValid(anIntArg))
{
// Do stuff here...
workedOK = true;
}
}
return workedOK;
}

That way I still have only one exit - and I have all the validations at the top. Obviously there are try...catch blocks involved but I wanted to put a simple layout.

- I would love to change the world, but they won’t give me the source code.

[CPallini]

There is few number of bad developers, like me, thinking the goto is not evil. :)

Veni, vidi, vici.

[Forogar]

Getting past the denial stage is the first step towards a cure. :laugh:

- I would love to change the world, but they won’t give me the source code.

[CPallini]

You know, now I have to use the goto on you... ;P

Veni, vidi, vici.

[Bill_Hallahan]

The book, "Classics In Software Engineering" has Dijkstra's excellent paper, "The Case Against The Goto". There was also another paper by another author in that book stating situations where the goto is useful. A goto is worthwhile in some very limited contexts. I found a related very short paper by Dijkstra online that is titled, "A Card Against The Goto" at http://www.cs.utexas.edu/users/EWD/transcriptions/EWD02xx/EWD215.html[^]. It is more of a philosophical outlook about the issue and doesn't go into the depth of the article in the book. It's also worthwhile reading the paragraphs under "Considered Harmful" at http://blogs.perl.org/users/erez_schatz/2011/07/rewriting-the-language.html[^]. That section tells about how when Dijkstra's article, "The Case Against The Goto" was submitted to the ACM magazine, the editor changed the title [to "Gotos Considered Harmful"] and created a furor! Two key sentences at the link above are: "It should cease to exist. Nothing in programming is definite. There is no single element that is either a silver bullet or the Antichrist." However, it is true that, in the vast majority of cases, using a goto can and should be avoided. But it's also a mistake to revile any code that contains a goto merely because the code contains one. By the way, I also agree with another poster that multiple returns in a function are undesirable, although I can see exceptions for this too. A single return in a function makes debugging so much easier. I make a serious effort to have only a single return, however, I have broken this guideline at times, particularly when working on critical legacy code where I wanted to minimize changes to the code. Here's a construct in pseudo-code that I've used in both C and C++ programs to avoid the need for gotos for multiple error cases. (By the way, I also always put the parenthesis in a statement, even for only one-line statements, because it makes the code easier to maintain. Typically, 85% of the cost, or time, spent on code is maintenance, so typically, code should be written to make it easy to maintain, as opposed to making

[Forogar]

I prefer:

// Some code here. Entering a section with lots of error checking.
// Some code goes here that sets an error condition.
if (!error)
{
// Some more code that sets an error condition.
if (!error)
{
// Even more code that sets an error condition.
if (!error)
{
// etc.
}
}
}
// The code continues here.

No "do...while" required. This also has the advantage that excessive indenting reminds the programmer that they need to break the code out into method calls to simplify the layout. Once it gets past four or five indents this becomes obvious. Better would be:

// Some code here. Entering a section with lots of error checking.
// Some code goes here that sets an error condition.
if (error)
{
// Report error details here.
}
else
{
// Some more code that sets an error condition.
if (error)
{
// Report error details here.
}
else
{
// Even more code that sets an error condition.
if (error)
{
// Report error details here.
}
else
{
// etc.
}
}
}
// The code continues here.

This way each error can be reported as necessary, perhaps with some cleanup or roll-back code.

- I would love to change the world, but they won’t give me the source code.