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Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Janis Papanagnou Newsgroups: comp.lang.c Subject: Re: goto considered helpful Date: Fri, 13 Dec 2024 14:50:26 +0100 Organization: A noiseless patient Spider Lines: 65 Message-ID: References: <87ldwx10gv.fsf@bsb.me.uk> <86ser1kgp5.fsf@linuxsc.com> <87ldwtzlc0.fsf@nosuchdomain.example.com> <87wmg5x4b1.fsf@nosuchdomain.example.com> <87jzc5wx3s.fsf@nosuchdomain.example.com> <87frmtwuzq.fsf@nosuchdomain.example.com> <20241212144454.00003b83@yahoo.com> <87wmg4vaeb.fsf@nosuchdomain.example.com> MIME-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Injection-Date: Fri, 13 Dec 2024 14:50:28 +0100 (CET) Injection-Info: dont-email.me; posting-host="9ac4af56cbfb1c4952f643dba36c3548"; logging-data="3627335"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+uVb8c7rCPCBwl2amZZ5uS" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 Cancel-Lock: sha1:VSM7hZeP+yoC2BMkveS5eNlUsZ4= X-Enigmail-Draft-Status: N1110 In-Reply-To: <87wmg4vaeb.fsf@nosuchdomain.example.com> Bytes: 4312 On 12.12.2024 22:50, Keith Thompson wrote: > > Backward gotos tend to be dangerous. Forward gotos are less so. I think I agree. > > Dijkstras original "Go To Statement Considered Harmful" letter was > written in 1968, at a time when many languages didn't necessarily > have the structured control constructs we've come to expect since > then. Using goto to implement a loop is almost always a bad idea, > but it's something that a modern C programmer probably wouldn't > even consider doing. Also in languages with control constructs it could be observed that there was a tendency to write "spaghetti-code" with 'goto'. And yes, that observation was certainly the reason for Dijkstra's paper. > > I agree that gotos have valid uses. I'm unable to provide references, but from faint memories I recall that exiting deeply nested loops was academically mentioned to be such a "valid" use of 'goto'. - And, frankly, I've rarely seen (or felt the need) for [sensible] other uses of 'goto'. One other use was to implement an (explicitly programmed, not table-driven) FSA (but personally I'm using other methods even for that application case). > > Here's an answer I wrote on Stack Exchange some years ago to the > question "Is using goto ever worthwhile?" : > [...] > > I would support adding named loops and labeled exit/continue to > a future version of C. I've used languages that have similar > features, and have found them very useful. Given that C doesn't > have multi-level break, I tend to agree that a goto statement is a > reasonable way to simulate it, often better than the alternatives. Yes, that might be the case. I'm not so sure about the idea of adding yet more jump-types. I consider 'break' as a camouflage to not make that "evil goto" too obvious and to restrict its "wildness" to a safer program context (that also makes things like stack-unrolling etc. superfluous). Give how rarely (IME) they seem to be used one 'goto' seems to be enough - but 'break' and 'continue' are useful in specific types of program logic, though 'break' with numbers as arguments (that I used once or twice in Unix shell) I'd not consider to be a good idea; labels would certainly be better. > [...] > > Here's an example of a small C program that completely avoids the > use of goto statements. I reserve the right to ridicule anyone who > takes this program seriously. Thanks for the warning! :-) > > [ source code with lots of setjmp/longjmp ] Janis