C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  query regarding namespaces          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Guest Posted: Tue Dec 12, 2006 10:11 am    Post subject: query regarding namespaces Hi everyone, I have the following piece of code, #include <stdio.h> #include "sample1.h" int x = 10; namespace first { int x = 5; } //using namespace first; int main() { using namespace first; printf("%d\n",x); return(0); } when i compile i get an error saying 'x' : ambiguous symbol, my requirement is to make sure main() uses variables in first namespace rather than global namespaces, can anyone help me regarding this? Back to top Guest Posted: Tue Dec 12, 2006 10:11 am    Post subject: Re: query regarding namespaces sam_cit (AT) yahoo (DOT) co.in wrote: Quote: But when i clearly mention that the compiler should use the namespace that i had specified instead of global one, in the sense, i want the compiler to look in the local namespace first for any references and if there are no match, search in global namespaces. Yes the first sentence is right, you have said the compiler to use namespace "first" but you have not said to not use the global namespace Back to top Ivan Vecerina Guest Posted: Tue Dec 12, 2006 10:11 am    Post subject: Re: query regarding namespaces <sam_cit (AT) yahoo (DOT) co.in> wrote in message news:1165907590.919757.286240 (AT) l12g2000cwl (DOT) googlegroups.com... : : #include <stdio.h> : #include "sample1.h" : : int x = 10; : : namespace first : { : int x = 5; : } : : //using namespace first; : : int main() : { : using namespace first; : printf("%d\n",x); : return(0); : } : : when i compile i get an error saying 'x' : ambiguous symbol, my : requirement is to make sure main() uses variables in first namespace : rather than global namespaces, can anyone help me regarding this? You can do it for a single identifier (e.g. first:) by adding the following declaration in main: using first:; // = like declaring a local x, will hide others You cannot do the same for a whole namespace. (And it would not be a good idea if it were possible, in my opinion, as the meaning of the code could accidentally change in subtle ways during maintenance...). hth --Ivan -- http://ivan.vecerina.com/contact/?subject=NG_POST <- email contact form Back to top Ian Collins Guest Posted: Tue Dec 12, 2006 10:11 am    Post subject: Re: query regarding namespaces eriwik (AT) student (DOT) chalmers.se wrote: Quote: Say that you in one of your files include map, string, iostream, vector and a few more and then goes using namespace std, imagine the chaos that might happen if there in one of those files existed a function or variable or such with the same name as one of yours, and without warning the compiler started to use that one instead of yours. At the very least it should warn you about it. It wouldn't, your variable would hide the one in std:: -- Ian Collins. Back to top Guest Posted: Tue Dec 12, 2006 10:11 am    Post subject: Re: query regarding namespaces Quote: Say that you in one of your files include map, string, iostream, vector and a few more and then goes using namespace std, imagine the chaos that might happen if there in one of those files existed a function or variable or such with the same name as one of yours, and without warning the compiler started to use that one instead of yours. At the very least it should warn you about it. -- But when i clearly mention that the compiler should use the namespace that i had specified instead of global one, in the sense, i want the compiler to look in the local namespace first for any references and if there are no match, search in global namespaces. Back to top Guest Posted: Tue Dec 12, 2006 10:11 am    Post subject: Re: query regarding namespaces Quote: You can do it for a single identifier (e.g. first:) by adding the following declaration in main: using first:; // = like declaring a local x, will hide others You cannot do the same for a whole namespace. (And it would not be a good idea if it were possible, in my opinion, as the meaning of the code could accidentally change in subtle ways during maintenance...). Well, i'm able to use the entire namespace as long as the identifer used in the name are not global and they are within many namespaces, #include <stdio.h> namespace second { int x = 10; } namespace first { int x = 5; } int main() { using namespace first; printf("%d\n",x); return(0); } i wonder why it has been made as a limitation when the identifer is global, after all global is yet another namespace... Back to top eriwik@student.chalmers.s Guest Posted: Tue Dec 12, 2006 10:11 am    Post subject: Re: query regarding namespaces On Dec 12, 8:34 am, sam_...@yahoo.co.in wrote: Quote: You can do it for a single identifier (e.g. first:) by adding the following declaration in main: using first:; // = like declaring a local x, will hide others You cannot do the same for a whole namespace. (And it would not be a good idea if it were possible, in my opinion, as the meaning of the code could accidentally change in subtle ways during maintenance...). Well, i'm able to use the entire namespace as long as the identifer used in the name are not global and they are within many namespaces, Yes, because now there is no collision, there is only one possible x. Quote: #include <stdio.h namespace second { int x = 10; }namespace first { int x = 5; }int main() { using namespace first; printf("%d\n",x); return(0); } i wonder why it has been made as a limitation when the identifer is global, after all global is yet another namespace... Say that you in one of your files include map, string, iostream, vector and a few more and then goes using namespace std, imagine the chaos that might happen if there in one of those files existed a function or variable or such with the same name as one of yours, and without warning the compiler started to use that one instead of yours. At the very least it should warn you about it. -- Erik Wikström 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.