C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Why isn't failbit reset on close() or open()??          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Mike Austin Guest Posted: Wed Sep 29, 2004 1:50 am    Post subject: Why isn't failbit reset on close() or open()?? It's the most annoying thing, and causes hours of frustration. Why can't it be resolved? Regards, Mike Austin Example: #include <iostream> #include <string> using namespace std; class DataStore { public: Store( string filename ) { datafile.open( filename.c_str(), ios::in | ios::binary ); if( !_datafile ) { datafile.clear(); // Will not work correctly without clearing datafile.open( filename.c_str(), ios::out | ios::binary ); datafile.write( "what the?", 9 ); } datafile.close(); datafile.open( filename.c_str(), ios::in | ios::out | ios::binary ); private: fstream datafile; }; Back to top Gernot Frisch Guest Posted: Wed Sep 29, 2004 1:15 pm    Post subject: Re: Why isn't failbit reset on close() or open()?? "Mike Austin" <mike (AT) mike-austin (DOT) com> schrieb im Newsbeitrag news:Wxo6d.644365$Gx4.110798 (AT) bgtnsc04-news (DOT) ops.worldnet.att.net... Quote: It's the most annoying thing, and causes hours of frustration. Why can't it be resolved? Regards, Mike Austin Example: #include <iostream #include #include <string using namespace std; class DataStore { public: Store( string filename ) { function declaration with no return type? Quote: datafile.open( filename.c_str(), ios::in | ios::binary ); if( !_datafile ) { '_datafile' is not declared. is it 'datafile' ? if (datafile) will always return 'true', since datafile is a valid object. Try datafile.is_open() here. Quote: datafile.clear(); // Will not work correctly without clearing // why not calling datafile.close() before re-opening it? Quote: datafile.open( filename.c_str(), ios::out | ios::binary ); datafile.write( "what the?", 9 ); } datafile.close(); datafile.open( filename.c_str(), ios::in | ios::out | ios::binary ); Here, a '}' is missing. Quote: private: fstream datafile; }; corrected code: #include #include <string> using namespace std; class DataStore { public: void Store( string filename ) { datafile.open( filename.c_str(), ios::in | ios::binary ); if(!datafile.is_open()) { datafile.clear(); // Will not work correctly without clearing datafile.open( filename.c_str(), ios::out | ios::binary ); datafile.write( "what the?", 9 ); } datafile.close(); datafile.open( filename.c_str(), ios::in | ios::out | ios::binary ); } private: fstream datafile; }; HTH, -- -Gernot int main(int argc, char** argv) {printf ("%silto%c%cf%cgl%ssic%ccom%c", "ma", 58, 'g', 64, "ba", 46, 10);} ________________________________________ Looking for a good game? Do it yourself! GLBasic - you can do www.GLBasic.com Back to top Mike Austin Guest Posted: Wed Sep 29, 2004 6:07 pm    Post subject: Re: Why isn't failbit reset on close() or open()?? "Gernot Frisch" <Me (AT) Privacy (DOT) net> wrote Quote: "Mike Austin" <mike (AT) mike-austin (DOT) com> schrieb im Newsbeitrag news:Wxo6d.644365$Gx4.110798 (AT) bgtnsc04-news (DOT) ops.worldnet.att.net... #include <iostream #include #include using namespace std; class DataStore { public: Store( string filename ) { function declaration with no return type? datafile.open( filename.c_str(), ios::in | ios::binary ); if( !_datafile ) { '_datafile' is not declared. is it 'datafile' ? if (datafile) will always return 'true', since datafile is a valid object. Try datafile.is_open() here. datafile.clear(); // Will not work correctly without clearing // why not calling datafile.close() before re-opening it? datafile.open( filename.c_str(), ios::out | ios::binary ); datafile.write( "what the?", 9 ); } datafile.close(); datafile.open( filename.c_str(), ios::in | ios::out | ios::binary ); Here, a '}' is missing. private: fstream datafile; }; corrected code: #include #include using namespace std; class DataStore { public: void Store( string filename ) { datafile.open( filename.c_str(), ios::in | ios::binary ); if(!datafile.is_open()) { datafile.clear(); // Will not work correctly without clearing datafile.open( filename.c_str(), ios::out | ios::binary ); datafile.write( "what the?", 9 ); } datafile.close(); datafile.open( filename.c_str(), ios::in | ios::out | ios::binary ); } private: fstream datafile; }; I'm sorry, I did a little editing before I posted and broke the code! The point is that you must use clear() before tying to open a file after failing in a previous attempt. close() or any other method has no effect. It just seems wrong.. calling open() should clear the failbit flag. I've been using C++ for years, mostly with OpenGL, and hate when I run into these time-wasting issues. Mike Austin Back to top John Harrison Guest Posted: Wed Sep 29, 2004 7:22 pm    Post subject: Re: Why isn't failbit reset on close() or open()?? "Mike Austin" <mike (AT) mike-austin (DOT) com> wrote Quote: It's the most annoying thing, and causes hours of frustration. Why can't it be resolved? I've heard it described as an oversight. As to why it can't be resolved, well I think it is being, but slowly. http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#409 john 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 Page 1 of 1   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.