Posted on 2002-05-14
I'm in sort of a dilemma, and I would like to hear your opinions, as experienced developers, on this matter. It's sort of an ethical issue, concerning the use of GOTOs.
In the old days, I used BASIC to program the Commodore 64, or later GWBASIC on the PC (We're talking 8088 here folks :). BASIC wasn't exactly known for its structured programming, and while some dialects included some rudimentary form of procedures (SUBroutines, called with GOSUB), programs mostly consisted of GOTOs to chain parts of the program together. I know mine did.
Later on, when I wised up and got access to a 286 (imagine that :), I ventured more into structured programming and got started with the language Pascal. From that point on, GOTOs became a no-no, the forbidden command that was only allowed for newbies and in batch scripts. I actually recoiled when I was once exposed to a Pascal program that used GOTOs exclusively to handle its flow control. When asked about this, I would always strongly advocate against the use of GOTOs and claim that anything using GOTOs could be rewritten to use only structured flow control statements, and become more readable at that.
Here is where my dilemma comes in... my brothers, I have sinned! Yes, I have done the unthinkable and actually used a GOTO in one of my programs... It seemed the most appriopiate construction for the problem at hand, and while I am proud that I have overcome my preconceptions and actually used a GOTO in a position where it was useful, still... part of me is in doubt whether or not I should have used a different construction, maybe something that I have overlooked.
I will explain the problem to you (it's not a very big one, just some pattern checking), and I hope you can help alleviate my guilt or tell me what a dumbass I am for overlooking an obvious structured way.
The point of the program is to check the syntax of HTML files. The matter of interest lies in a routine that ignores comments. Once it is determined that a comment has started (by the encounter of the character sequence <! ), the program keeps on reading characters from the input string until a sequential -> is found. That is, a dash followed by a "greater than" sign. If just a dash is encountered, followed by something else than a greater than sign, the comment has not yet ended and the program should keep checking. Also, if a greater than sign is encountered that is not preceded by a dash, the check should go on.
This is the code that I eventually used (NextChar is a routine that reads the next character from the input string and places it in FChar; I used some more constants here that have been omitted for clarity):
While FChar <> '-' Do NextChar;
If FChar <> '>' Then Goto checkend;
Quite simple, yes? My question is, is there a way that I could have written this with structured statements such as while and if, and if so, would it have been clearer? Or is my use of the goto justified?
I'd appreciate any input you might have.