C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  coding style question Goto page 1, 2, 3  Next          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message Ask Guest Posted: Wed Dec 21, 2005 1:07 pm    Post subject: coding style question This is a question related to style. Which one is preferrable between the two below - if ( var == 0) -----(1) if ( 0 == var) -----(2) Does the 2nd one look awkward ? I prefer the 2nd one in which all constants, literals are kept at the left side of the operator "==". This is because if somebody accidently types "=" instead of "==", the code won't compile. if (var=0) - compiles if (0=var) - doesn't compile. So the second one is safer. Your comments ? Thanks [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Roland Csaszar Guest Posted: Wed Dec 21, 2005 5:08 pm    Post subject: Re: coding style question Hi, At 21 Dec 2005 08:07:11 -0500, Ask wrote: Quote: I prefer the 2nd one in which all constants, literals are kept at the left side of the operator "==". This is because if somebody accidently types "=" instead of "==", the code won't compile. if (var=0) - compiles if (0=var) - doesn't compile. So the second one is safer. Your comments ? Any compiler should (and does, at least all i know) throw a warning or info on such constructs. GCC for example says "warning: suggest parentheses around assignment used as truth value" (when compiled with -Wall). Actually, at least for me, the second one is harder to comprehend, in everyday life you would say something like "if the box is empty" and not "if empty is the box" and i tend to write things down that way. Regards, Roland -- Roland Csaszar ----------- \ /// -------------- +43 316 495 2129 Software Development ------ \ /// ----------- http://www.knapp.com KNAPP Logistics Automation - \V// - mailto:roland.csaszar (AT) knapp (DOT) com [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Dervish Guest Posted: Wed Dec 21, 2005 5:09 pm    Post subject: Re: coding style question Quote: if ( var == 0) -----(1) if ( 0 == var) -----(2) In this specific example one should write if ( !var) -----(3) If there is a comparison with non zero value e.g. if ( var == 3) both variants acceptable. However if one writes if ( var = 3) reasonable compiler warns about possible error. It does not stop compilation, but can help developer to find real error. Nevertheless for my mind if ( 3 == var) construction is hardly readable. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Jim Chaney Guest Posted: Wed Dec 21, 2005 5:12 pm    Post subject: Re: coding style question Ask wrote: Quote: This is a question related to style. Which one is preferrable between the two below - if ( var == 0) -----(1) if ( 0 == var) -----(2) Does the 2nd one look awkward ? Yes. Quote: I prefer the 2nd one in which all constants, literals are kept at the left side of the operator "==". This is because if somebody accidently types "=" instead of "==", the code won't compile. if (var=0) - compiles if (0=var) - doesn't compile. So the second one is safer. Your comments ? Almost all compilers will issue a warning about the above example (eg. assignment in conditional expression) at their most pedantic settings. I would recommend you enable these options and turn on warnings as errors also. IMO you shouldnt give up code readability for something the compiler can easily catch. Jim [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Niek Sanders Guest Posted: Wed Dec 21, 2005 5:13 pm    Post subject: Re: coding style question Ask wrote: Quote: This is a question related to style. Which one is preferrable between the two below - if ( var == 0) -----(1) if ( 0 == var) -----(2) Does the 2nd one look awkward ? I find that the second variant looks very funky, though I've certainly seen people use the style before. I use the first style; it comes closer to the way I think when it comes to both programming and mathematics in general. The voice inside my head says "if x is 2...", not "if 2 is x...". Heck, the latter even carries a connotation that 2 is somehow not variant. Yes, I could retrain myself to think in the latter style, but I've never been bitten by this issue badly enough for me to care. So you can keep asking if "black is the apple?", while I'll stick with "is the apple black?" Cheers, Niek Sanders http://www.cis.rit.edu/~njs8030/ [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Robert Kindred Guest Posted: Wed Dec 21, 2005 5:14 pm    Post subject: Re: coding style question "Ask" <ask.q (AT) indiatimes (DOT) com> wrote Quote: This is a question related to style. Which one is preferrable between the two below - if ( var == 0) -----(1) if ( 0 == var) -----(2) [] I prefer the 2nd one in which all constants, literals are kept at the left side of the operator "==". This is because if somebody accidently types "=" instead of "==", the code won't compile. I like your safety precaution, but it does not allow the operator== to be overloaded if var is a class. Robert Kindred [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Francis Glassborow Guest Posted: Thu Dec 22, 2005 3:07 am    Post subject: Re: coding style question In article <1135145437.686421.301420 (AT) g14g2000cwa (DOT) googlegroups.com>, Ask <ask.q (AT) indiatimes (DOT) com> writes Quote: This is a question related to style. Which one is preferrable between the two below - if ( var == 0) -----(1) if ( 0 == var) -----(2) Does the 2nd one look awkward ? I prefer the 2nd one in which all constants, literals are kept at the left side of the operator "==". This is because if somebody accidently types "=" instead of "==", the code won't compile. if (var=0) - compiles if (0=var) - doesn't compile. So the second one is safer. Your comments ? Most compilers raise warnings for assignment in conditionals at least for a sufficiently high setting of warnings. And how would you deal with miss-typing i == 0; for i=0; Quite possible, particularly on keyboards that are getting old. -- Francis Glassborow ACCU Author of 'You Can Do It!' see http://www.spellen.org/youcandoit For project ideas and contributions: http://www.spellen.org/youcandoit/projects [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Braden McDaniel Guest Posted: Thu Dec 22, 2005 3:13 am    Post subject: Re: coding style question On Wed, 2005-12-21 at 08:07 -0500, Ask wrote: Quote: This is a question related to style. Which one is preferrable between the two below - if ( var == 0) -----(1) if ( 0 == var) -----(2) Does the 2nd one look awkward ? Yes. Quote: I prefer the 2nd one in which all constants, literals are kept at the left side of the operator "==". This is because if somebody accidently types "=" instead of "==", the code won't compile. if (var=0) - compiles if (0=var) - doesn't compile. So the second one is safer. Your comments ? I'm skeptical of the value of any convention that makes code harder to read. IME, this error doesn't come up frequently enough to justify the mental inversion imposed by the convention you suggest. If one is sufficiently conscientious to apply such a convention consistently, one is probably capable of applying similar discipline to avoid the problem in the first place. -- Braden McDaniel e-mail: <braden (AT) endoframe (DOT) com> <http://endoframe.com> Jabber: <braden (AT) jabber (DOT) org> [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Bob Hairgrove Guest Posted: Thu Dec 22, 2005 3:13 am    Post subject: Re: coding style question On 21 Dec 2005 08:07:11 -0500, "Ask" <ask.q (AT) indiatimes (DOT) com> wrote: Quote: This is a question related to style. Which one is preferrable between the two below - if ( var == 0) -----(1) if ( 0 == var) -----(2) Does the 2nd one look awkward ? I prefer the 2nd one in which all constants, literals are kept at the left side of the operator "==". This is because if somebody accidently types "=" instead of "==", the code won't compile. if (var=0) - compiles if (0=var) - doesn't compile. So the second one is safer. Your comments ? Safest is IMHO: if (!var) { /*...*/} Of course, when comparing to any other value, number 2 above has strong merits, as you have illustrated. -- Bob Hairgrove [email]NoSpamPlease (AT) Home (DOT) com[/email] [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Bob Hairgrove Guest Posted: Thu Dec 22, 2005 3:16 am    Post subject: Re: coding style question On 21 Dec 2005 12:14:01 -0500, "Robert Kindred" <RKindred (AT) SwRI (DOT) edu> wrote: Quote: "Ask" <ask.q (AT) indiatimes (DOT) com> wrote in message news:1135145437.686421.301420 (AT) g14g2000cwa (DOT) googlegroups.com... This is a question related to style. Which one is preferrable between the two below - if ( var == 0) -----(1) if ( 0 == var) -----(2) [] I prefer the 2nd one in which all constants, literals are kept at the left side of the operator "==". This is because if somebody accidently types "=" instead of "==", the code won't compile. I like your safety precaution, but it does not allow the operator== to be overloaded if var is a class. It's possible to overload operator== as a non-member operator taking arguments of (int, class_type const &) so that the comparison with the literal on the left would work (assuming that class_type is the type of "var" in the above example). -- Bob Hairgrove [email]NoSpamPlease (AT) Home (DOT) com[/email] [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top wizofaus@hotmail.com Guest Posted: Thu Dec 22, 2005 12:11 pm    Post subject: Re: coding style question Francis Glassborow wrote: Quote: Most compilers raise warnings for assignment in conditionals at least for a sufficiently high setting of warnings. And how would you deal with miss-typing i == 0; for i=0; Quite possible, particularly on keyboards that are getting old. Happens with brand new keyboards too - it's called "hypercorrection". Like using "whom" where it actually should be "who" etc. etc. I've done it more than once, and compilers often don't even bother warning about it. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Ask Guest Posted: Thu Dec 22, 2005 12:13 pm    Post subject: Re: coding style question Quote: Does the 2nd one look awkward ? Yes. So the second one is safer. Your comments ? I'm skeptical of the value of any convention that makes code harder to read. IME, this error doesn't come up frequently enough to justify the mental inversion imposed by the convention you suggest. If one is sufficiently conscientious to apply such a convention consistently, one is probably capable of applying similar discipline to avoid the problem in the first place. "Condition Format" at the following site mentions this - http://www.possibility.com/Cpp/CppCodingStandard.html Also, compiler doesn't throw warning in this case y = (x = 4) ? 10 : 5; [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Martin Guest Posted: Thu Dec 22, 2005 12:13 pm    Post subject: Re: coding style question I prefer the first one but sometimes use the second one when the left expression is very long. instead of if (static_cast<int>(longvariable.longmember()) == 2) I write if (2 == static_cast<int>(longvariable.longmember())) Often I understand from the context or comments what the expression does but don't always remember which operator is used in the comparison. With the first version I might need to scroll the display to see the operator. For the same reason I sometimes put && and || first on second row instead of last on the first. if (longexpression1 Quote: | expression2) [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Carlos Moreno Guest Posted: Thu Dec 22, 2005 12:14 pm    Post subject: Re: coding style question Niek Sanders wrote: Quote: Ask wrote: This is a question related to style. Which one is preferrable between the two below - if ( var == 0) -----(1) if ( 0 == var) -----(2) Does the 2nd one look awkward ? Yes, I could retrain myself to think in the latter style, but I've never been bitten by this issue badly enough for me to care. So you can keep asking if "black is the apple?", while I'll stick with "is the apple black?" Nice example! However, there are situations where we are forced to "phrase" things in an awkward way: if (! is_empty()) // this could be used as an argument against // the "is_" as part of the name if (a == 1 || > 10) // that's how we say it in English -- but it // doesn't work in most programming languages... One example where IMO the constant looks much nicer on the left is: if (0 < a && a < 10) (suggests the standard math notation 0 < a < 10 ) Cheers, Carlos -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Mateusz Łoskot Guest Posted: Thu Dec 22, 2005 12:15 pm    Post subject: Re: coding style question Ask wrote: Quote: This is a question related to style. Which one is preferrable between the two below - if ( var == 0) -----(1) if ( 0 == var) -----(2) Does the 2nd one look awkward ? No. One can get familiar easily with the second style as fast as with the first one. IMHO the second is safer, because that simple rule will prevent you from possbile typos. Cheers -- Mateusz Łoskot http://mateusz.loskot.net [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ Language (Moderated) All times are GMT Goto page 1, 2, 3  Next Page 1 of 3   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.