C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  2 very basic qns          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message mescaline Guest Posted: Mon Dec 29, 2003 2:23 am    Post subject: 2 very basic qns 1. Why does C++ require the int in: int main(){...} (is there a special reason for int, why not void,etc...?) 2. What purpose does the return 0; serve at the end of the main program: (when the program is run successfully and the " return 0; " statement is encountered, what exactly happens -- where is the 0 returned?) thanks Back to top Ron Natalie Guest Posted: Mon Dec 29, 2003 2:31 am    Post subject: Re: 2 very basic qns "mescaline" <apt2003 (AT) columbia (DOT) edu> wrote Quote: 1. Why does C++ require the int in: int main(){...} (is there a special reason for int, why not void,etc...?) Are you talking about main specifically or functions in general. The "implicit" int return has been removed from the language because it wasn't exactly consistant. As far as why MAIN itself must return int. Tradition is the major reason. Quote: 2. What purpose does the return 0; serve at the end of the main program: (when the program is run successfully and the " return 0; " statement is encountered, what exactly happens -- where is the 0 returned?) It's an implementation specific success code. On some systems it gets passed back to the invoked program (like UNIX). On some systems the environment calls a system call indicating normal termination where as the error returns from exit/main call the error system call. On others a zero means silent exit while a non-zero return cause an error popup. Others the value is just discarded. Back to top Gary Labowitz Guest Posted: Mon Dec 29, 2003 5:59 am    Post subject: Re: 2 very basic qns "Ron Natalie" <ron (AT) sensor (DOT) com> wrote Quote: "mescaline" <apt2003 (AT) columbia (DOT) edu> wrote 1. Why does C++ require the int in: int main(){...} (is there a special reason for int, why not void,etc...?) Are you talking about main specifically or functions in general. The "implicit" int return has been removed from the language because it wasn't exactly consistant. As far as why MAIN itself must return int. Tradition is the major reason. Well, not really. The standards group, that works on defining the language, has published a standard that main must return an int. Unless you want to call standards a tradition... -- Gary Back to top Ron Natalie Guest Posted: Mon Dec 29, 2003 1:01 pm    Post subject: Re: 2 very basic qns "Gary Labowitz" <glabowitz (AT) comcast (DOT) net> wrote Quote: Well, not really. The standards group, that works on defining the language, has published a standard that main must return an int. Unless you want to call standards a tradition... -- I know that. The poster asked for WHY. The language is defined by the standard, but the standards people had reasons for the requirements they set down. The reason main is REQUIRED BY THE STANDARD to return in is TRADITION. Main has always returned int, ever since the early days of C. Partially this was because C didn't even have a void type in the beginning, then later because UNIX relied heavily on using the numeric return from programs. Back to top mescaline Guest Posted: Mon Dec 29, 2003 2:23 pm    Post subject: Re: 2 very basic qns "Gary Labowitz" <glabowitz (AT) comcast (DOT) net> wrote Quote: "Ron Natalie" <ron (AT) sensor (DOT) com> wrote in message news:3fef4a9c$0$31832$9a6e19ea (AT) news (DOT) newshosting.com... "mescaline" <apt2003 (AT) columbia (DOT) edu> wrote in message news:e54f0744.0312281823.2db5f4b2 (AT) posting (DOT) google.com... 1. Why does C++ require the int in: int main(){...} (is there a special reason for int, why not void,etc...?) Are you talking about main specifically or functions in general. The "implicit" int return has been removed from the language because it wasn't exactly consistant. As far as why MAIN itself must return int. Tradition is the major reason. Well, not really. The standards group, that works on defining the language, has published a standard that main must return an int. Unless you want to call standards a tradition... Conversely, does it always return a non-zero value, when there's *any* error with the compiling? thanks Back to top Ron Natalie Guest Posted: Mon Dec 29, 2003 2:51 pm    Post subject: Re: 2 very basic qns "mescaline" <apt2003 (AT) columbia (DOT) edu> wrote Quote: Conversely, does it always return a non-zero value, when there's *any* error with the compiling? If you had problems compiling, you're not likely going to get as far as having a main function to run. 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