C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  braces needed? Goto page 1, 2  Next          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Jason Guest Posted: Sat Jan 31, 2004 2:02 am    Post subject: braces needed? Programming recently I was the habit of leaving out the braces on if statements if the branch only applied to a single line, assuming it would all work and be equivalent to "if(condition) { statement; }" I implemented an algorithm and it did not work for a while and when i tracked the problem down it was as if a certain action was not being done from one of these if statements that did not have a brace, so I placed all if statements in braces and it worked as expected. This was not a result of misunderstanding on my part such as including 2 statements under the braceless if and I know indentation is not important, the statements were usually all on one line anyhow. It appeared to work ok when I first started doing it, but not when there was a few in a row or near each other inside while loops and such like. In some parts of my code I have neglected to change them to braces without any problems, confusing me. I also sometimes feel the desire to omit braces from while and for loops because i find them irritating and like to shorten my code. Am I able to avoid braces or not? Is it guaranteed to work or do different compilers produce different results? If I have code that works perfectly now and all I do is remove braces from single statement if, for and while loops, is it guaranteed to make no difference or am I naive to some other potential problem? thanks for clarifying. Back to top David Harmon Guest Posted: Sat Jan 31, 2004 3:28 am    Post subject: Re: braces needed? On Sat, 31 Jan 2004 02:02:04 +0000 (UTC) in comp.lang.c++, "Jason" <jason.carney1 (AT) btinternet (DOT) com> was alleged to have written: Quote: Is it guaranteed to work or do different compilers produce different results? If I have code that works perfectly now and all I do is remove braces from single statement if, for and while loops, is it guaranteed to make no difference or am I naive to some other potential problem? It is guaranteed to work the same on all compilers. This part of the language syntax has been well defined from the very beginning of C, and it would be a huge shock to find a compiler that got it wrong. The thing controlled by an "if" or "while" is conceptually a single statement. Multiple statements with braces around them are considered a single "compound statement". If you want, you can put braces around a group of statements that have nothing to do with any "if" or "while". I prefer to omit redundant braces for an "if" or "while" that controls a single statement, but there is nothing terribly wrong about using them every time. Some people say it reduces the likelihood of error, and based on your experience maybe it does. I find it nicer to read the code without them, but of course you have to understand the language rules. Back to top Jason Guest Posted: Sat Jan 31, 2004 3:54 am    Post subject: Re: braces needed? "David Harmon" <source (AT) netcom (DOT) com> wrote Quote: On Sat, 31 Jan 2004 02:02:04 +0000 (UTC) in comp.lang.c++, "Jason" [email]jason.carney1 (AT) btinternet (DOT) com[/email]> was alleged to have written: Is it guaranteed to work or do different compilers produce different results? If I have code that works perfectly now and all I do is remove braces from single statement if, for and while loops, is it guaranteed to make no difference or am I naive to some other potential problem? It is guaranteed to work the same on all compilers. This part of the language syntax has been well defined from the very beginning of C, and it would be a huge shock to find a compiler that got it wrong. The thing controlled by an "if" or "while" is conceptually a single statement. Multiple statements with braces around them are considered a single "compound statement". If you want, you can put braces around a group of statements that have nothing to do with any "if" or "while". I prefer to omit redundant braces for an "if" or "while" that controls a single statement, but there is nothing terribly wrong about using them every time. Some people say it reduces the likelihood of error, and based on your experience maybe it does. I find it nicer to read the code without them, but of course you have to understand the language rules. Thanks for the reply(grr @ dig:)). I've never looked at the syntax rules for a programming language I've used, I've just used it, but now I'm interested, any online references to the complete syntax of c++ so I can understand all the language rules? all i get on google is fricking adverts for books. Quote: Back to top Jack Klein Guest Posted: Sat Jan 31, 2004 4:35 am    Post subject: Re: braces needed? On Sat, 31 Jan 2004 02:02:04 +0000 (UTC), "Jason" <jason.carney1 (AT) btinternet (DOT) com> wrote in comp.lang.c++: Quote: Programming recently I was the habit of leaving out the braces on if statements if the branch only applied to a single line, assuming it would all work and be equivalent to "if(condition) { statement; }" I implemented an algorithm and it did not work for a while and when i tracked the problem down it was as if a certain action was not being done from one of these if statements that did not have a brace, so I placed all if statements in braces and it worked as expected. This was not a result of misunderstanding on my part such as including 2 statements under the braceless if and I know indentation is not important, the statements were usually all on one line anyhow. It appeared to work ok when I first started doing it, but not when there was a few in a row or near each other inside while loops and such like. In some parts of my code I have neglected to change them to braces without any problems, confusing me. I also sometimes feel the desire to omit braces from while and for loops because i find them irritating and like to shorten my code. Am I able to avoid braces or not? Is it guaranteed to work or do different compilers produce different results? If I have code that works perfectly now and all I do is remove braces from single statement if, for and while loops, is it guaranteed to make no difference or am I naive to some other potential problem? thanks for clarifying. Without showing us some of the code that behaved incorrectly, and what you changed it to to make it behave the way you wanted it to, it is difficult to say for sure what went wrong. Most likely you had an "else" or "elseif" matched up to the wrong "if". I have never seen a professional coding standard that did not require the braces around all controlled clauses, even if they were only a single statement. Nor will there ever be one anyplace I work where I have any measure of control over the coding standard. There is just too much chance for error, not only when writing the original code, but even more so later when the code is modified for defect fixing or upgrade. -- Jack Klein Home: http://JK-Technology.Com FAQs for comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html comp.lang.c++ http://www.parashift.com/c++-faq-lite/ alt.comp.lang.learn.c-c++ http://www.contrib.andrew.cmu.edu/~ajo/docs/FAQ-acllc.html Back to top Gianni Mariani Guest Posted: Sat Jan 31, 2004 5:23 am    Post subject: Re: braces needed? Jason wrote: Quote: "David Harmon" <source (AT) netcom (DOT) com> wrote in message news:401d1d83.17745936 (AT) news (DOT) west.earthlink.net... On Sat, 31 Jan 2004 02:02:04 +0000 (UTC) in comp.lang.c++, "Jason" [email]jason.carney1 (AT) btinternet (DOT) com[/email]> was alleged to have written: Is it guaranteed to work or do different compilers produce different results? If I have code that works perfectly now and all I do is remove braces from single statement if, for and while loops, is it guaranteed to make no difference or am I naive to some other potential problem? It is guaranteed to work the same on all compilers. This part of the language syntax has been well defined from the very beginning of C, and it would be a huge shock to find a compiler that got it wrong. The thing controlled by an "if" or "while" is conceptually a single statement. Multiple statements with braces around them are considered a single "compound statement". If you want, you can put braces around a group of statements that have nothing to do with any "if" or "while". I prefer to omit redundant braces for an "if" or "while" that controls a I have a policy of allways having a brace. In fact, if I had a compiler option that would refuse anything but compound statements on if/else/while etc I would hardwire it on. - simply because that one behaviour if it eliminates one instance of an error I could make is worth the price - I've seen that error happen with multiple people more than I can count. Quote: single statement, but there is nothing terribly wrong about using them every time. Some people say it reduces the likelihood of error, and based on your experience maybe it does. I find it nicer to read the code without them, but of course you have to understand the language rules. Thanks for the reply(grr @ dig:)). I've never looked at the syntax rules for a programming language I've used, I've just used it, but now I'm interested, any online references to the complete syntax of c++ so I can understand all the language rules? all i get on google is fricking adverts for books. Occasionally it's good to buy books. Stroustrup's "The C++ Programming Language" has a grammmer section which is an interesting reference. Here's a google hit: http://www.csci.csusb.edu/dick/c++std/cd2/gram.html Back to top Jack Klein Guest Posted: Sat Jan 31, 2004 5:32 am    Post subject: Re: braces needed? On Fri, 30 Jan 2004 22:34:01 -0700, "Jonathan Turkanis" <technews (AT) kangaroologic (DOT) com> wrote in comp.lang.c++: Quote: "Jack Klein" <jackklein (AT) spamcop (DOT) net> wrote in message: I have never seen a professional coding standard that did not require the braces around all controlled clauses, even if they were only a single statement. Nor will there ever be one anyplace I work where I have any measure of control over the coding standard. There is just too much chance for error, not only when writing the original code, but even more so later when the code is modified for defect fixing or upgrade. Certainly requiring braces seems to have wide acceptance, but your statement is an exaggeration. Glancing quickly through the standard, the Dinkumware standard library which ships with VC7.1, and the Boost source, I find numerous uses of 'if' without braces. Generally the meaning of such code is immediately clear. Just serach for 'if (' in the standard. Jonathan The examples in the C and C++ standards are not, nor are they intended to be, examples of a particularly robust coding style. Investigate the literature and find the number of defects associated with the practice of omitting braces. -- Jack Klein Home: http://JK-Technology.Com FAQs for comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html comp.lang.c++ http://www.parashift.com/c++-faq-lite/ alt.comp.lang.learn.c-c++ http://www.contrib.andrew.cmu.edu/~ajo/docs/FAQ-acllc.html Back to top Jonathan Turkanis Guest Posted: Sat Jan 31, 2004 5:34 am    Post subject: Re: braces needed? "Jack Klein" <jackklein (AT) spamcop (DOT) net> wrote in message: Quote: I have never seen a professional coding standard that did not require the braces around all controlled clauses, even if they were only a single statement. Nor will there ever be one anyplace I work where I have any measure of control over the coding standard. There is just too much chance for error, not only when writing the original code, but even more so later when the code is modified for defect fixing or upgrade. Certainly requiring braces seems to have wide acceptance, but your statement is an exaggeration. Glancing quickly through the standard, the Dinkumware standard library which ships with VC7.1, and the Boost source, I find numerous uses of 'if' without braces. Generally the meaning of such code is immediately clear. Just serach for 'if (' in the standard. Jonathan Back to top Jonathan Turkanis Guest Posted: Sat Jan 31, 2004 5:52 am    Post subject: Re: braces needed? "Jack Klein" <jackklein (AT) spamcop (DOT) net> wrote in message: Quote: On Fri, 30 Jan 2004 22:34:01 -0700, "Jonathan Turkanis": Certainly requiring braces seems to have wide acceptance, but your statement is an exaggeration. Glancing quickly through the standard, the Dinkumware standard library which ships with VC7.1, and the Boost source, I find numerous uses of 'if' without braces. Generally the meaning of such code is immediately clear. Just serach for 'if (' in the standard. Jonathan The examples in the C and C++ standards are not, nor are they intended to be, examples of a particularly robust coding style. Investigate the literature and find the number of defects associated with the practice of omitting braces. That's an interesting response. You seemed to claiming general acceptance of the pratice of including braces everywhere. (Maybe I misinterpretted you.) Notice that I did not disagree that this is a wise practice. I simply offered some evidence that the practive is not nearly as widespread as you implied, even in code from very reputable sources. Now you tell me to 'investigate the literature'. You're the one making the argument -- it's your responsibility to provide evidence for your position. Of course, the examples from the standard are not intended to be examples of robust coding style. But certainly they are not examples of bad style (excpet for those flagged as errors). Jonathan Back to top Jason Guest Posted: Sat Jan 31, 2004 5:57 am    Post subject: Re: braces needed? "> Quote: Occasionally it's good to buy books. Stroustrup's "The C++ Programming Language" has a grammmer section which is an interesting reference. thanks for the tip, I wish I had bought that book recently in preference to the C++ Standard Library by Josuttis, which I have hardly needed to use. I guess i can read about iterators and templates when i feel like it, but I dont find it very helpful as I only ever used vector, string and few stream objects from the STL. The only reason I did not buy Stroustrup was because I have experience of reading K & R for the c language and assumed it would be similar in style ie a little bit on the formal side and rather dull. I suppose I will buy it anyway at some point. thanks again. Back to top David Harmon Guest Posted: Sat Jan 31, 2004 7:06 am    Post subject: Re: braces needed? On 31 Jan 2004 00:23:55 EST in comp.lang.c++, Gianni Mariani <gi2nospam (AT) mariani (DOT) ws> was alleged to have written: Quote: I have a policy of allways having a brace. In fact, if I had a compiler option that would refuse anything but compound statements on if/else/while etc I would hardwire it on. I would expect that almost any "lint" type product would allow you to check for that. Back to top Nick Hounsome Guest Posted: Sat Jan 31, 2004 3:25 pm    Post subject: Re: braces needed? "Jason" <jason.carney1 (AT) btinternet (DOT) com> wrote Quote: Programming recently I was the habit of leaving out the braces on if statements if the branch only applied to a single line, assuming it would all work and be equivalent to "if(condition) { statement; }" I implemented an algorithm and it did not work for a while and when i tracked the problem down it was as if a certain action was not being done from one of these if statements that did not have a brace, so I placed all if statements in braces and it worked as expected. This was not a result of misunderstanding on my part such as including 2 statements under the braceless if and I know indentation is not important, the statements were usually all on one line anyhow. It appeared to work ok when I first started doing it, but not when there was a few in a row or near each other inside while loops and such like. In some parts of my code I have neglected to change them to braces without any problems, confusing me. I also sometimes feel the desire to omit braces from while and for loops because i find them irritating and like to shorten my code. Am I able to avoid braces or not? Is it guaranteed to work or do different compilers produce different results? If I have code that works perfectly now and all I do is remove braces from single statement if, for and while loops, is it guaranteed to make no difference or am I naive to some other potential problem? thanks for clarifying. The main problem with not including braces that I come across is poorly written macros particularly debug ones or ones requiring a local variable For example: #define DEBUG(s) if( debug ) puts(s) This works ok for if( x > 3 ) DEBUG("too big"); But fails miserably the moment you add an else/else if clause: if( x > 3 ) DEBUG("too big"); else { // this will only happen if x >3 && !debug } I use the braces but if you don't be sure to use the do..while trick - #define DEBUG(s) do { if(debug) puts(s); /* local vars ... whatever */} while(false) This allows you to use the macro almost exactly as a function returning void and a good compiler will probably impose no overhead (although it may warn you which is annoying). Back to top lilburne Guest Posted: Sat Jan 31, 2004 9:14 pm    Post subject: Re: braces needed? Jonathan Turkanis wrote: Quote: "Jack Klein" <jackklein (AT) spamcop (DOT) net> wrote in message: There is just too much chance for error, not only when writing the original code, but even more so later when the code is modified for defect fixing or upgrade. Certainly requiring braces seems to have wide acceptance, but your statement is an exaggeration. Glancing quickly through the standard, the Dinkumware standard library which ships with VC7.1, and the Boost source, I find numerous uses of 'if' without braces. Generally the meaning of such code is immediately clear. Perhaps they don't have coding standards, or neglect them from time to time. Our coding standard requires braces around all control statements and even 'outlaws' single line variants: if (a < b) function(); for (int x = 0; x < y; ++x) function(); yet from time to time you'll find such examples in the codebase even written by the originators of the standard. They get to fix it. Back to top Jonathan Turkanis Guest Posted: Sat Jan 31, 2004 9:38 pm    Post subject: Re: braces needed? "lilburne" <lilburne (AT) godzilla (DOT) net> wrote Quote: Jonathan Turkanis wrote: "Jack Klein" <jackklein (AT) spamcop (DOT) net> wrote in message: Certainly requiring braces seems to have wide acceptance, but your statement is an exaggeration. Glancing quickly through the standard, the Dinkumware standard library which ships with VC7.1, and the Boost source, I find numerous uses of 'if' without braces. Generally the meaning of such code is immediately clear. Perhaps they don't have coding standards, or neglect them from time to time. Our coding standard requires braces around all control statements and even 'outlaws' single line variants: if (a < b) function(); for (int x = 0; x < y; ++x) function(); yet from time to time you'll find such examples in the codebase even written by the originators of the standard. They get to fix it. Maybe this policy should be adopted universely. My only point was that it hasn't been even by people familiar with the problems which have been mentioned in this thread. Boost doesn't have coding standards -- just some general guidelines. Obviously the standard doesn't have coding standards. But I'd be surprised to learn Dinkumware doesn't. Jonathan Back to top lilburne Guest Posted: Sat Jan 31, 2004 9:51 pm    Post subject: Re: braces needed? Jonathan Turkanis wrote: Quote: Boost doesn't have coding standards -- just some general guidelines. Obviously the standard doesn't have coding standards. But I'd be surprised to learn Dinkumware doesn't. Maybe they do, or maybe it depends on seniority of the person writing the code, or maybe occasionally things get missed, or maybe they didn't want people whining about 'bloat' in header files. You can't tell just by examining the code. There are consideration other than just readability. Personally, like others that have responded to this thread, I consider that using braces removes a class of bugs and is helpful for maintainance. Also as with Jack Klein if I have any control of a coding standard I'd be insisting on braces around all control statements. Back to top Jonathan Turkanis Guest Posted: Sat Jan 31, 2004 10:15 pm    Post subject: Re: braces needed? "lilburne" <lilburne (AT) godzilla (DOT) net> wrote in message: Quote: There are consideration other than just readability. Personally, like others that have responded to this thread, I consider that using braces removes a class of bugs and is helpful for maintainance. Also as with Jack Klein if I have any control of a coding standard I'd be insisting on braces around all control statements. I thought Jack Klein was saying, 'you'd better get used to using braces, since their in (just about) every professional coding standard', not 'I wish I could add the requirement to my company's coding standards.' I guess I'll repeat one last time: I'm not against requiring braces. Jonathan 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 (comp.lang.c++) All times are GMT Goto page 1, 2  Next Page 1 of 2   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.