C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Calling functions in other files...          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Charlie Guest Posted: Wed Sep 29, 2004 8:40 pm    Post subject: Calling functions in other files... Ok, I have three files: calc.cpp, calc.h, and ui.cpp. I would like to call a function that is located in ui.cpp from main() in calc.cpp. Both files have calc.h included, but when I tried to include ui.cpp in calc.cpp, it gave me an error due to multiple instances of the same function's. How do I call my function that is in ui.cpp from calc.cpp? Back to top Phlip Guest Posted: Wed Sep 29, 2004 8:46 pm    Post subject: Re: Calling functions in other files... Charlie wrote: Quote: Ok, I have three files: calc.cpp, calc.h, and ui.cpp. I would like to call a function that is located in ui.cpp from main() in calc.cpp. Both files have calc.h included, but when I tried to include ui.cpp in calc.cpp, it gave me an error due to multiple instances of the same function's. How do I call my function that is in ui.cpp from calc.cpp? Your compiler must have come with sample programs showing how to link more than one object file, and you can find a tutorial for it on Google. -- Phlip http://industrialxp.org/community/bin/view/Main/TestFirstUserInterfaces Back to top John Harrison Guest Posted: Wed Sep 29, 2004 9:27 pm    Post subject: Re: Calling functions in other files... "Charlie" <charlie.lamothe (AT) gmail (DOT) com> wrote Quote: Ok, I have three files: calc.cpp, calc.h, and ui.cpp. I would like to call a function that is located in ui.cpp from main() in calc.cpp. Both files have calc.h included, but when I tried to include ui.cpp in calc.cpp, it gave me an error due to multiple instances of the same function's. How do I call my function that is in ui.cpp from calc.cpp? You never include one source file in another. You should write a header file called ui.h that declares the function in ui.cpp that you want to call. Then include that header file in both ui.cpp and calc.cpp. This is basic stuff, any decent C++ book should explain this. john Back to top Nils O. Selåsdal Guest Posted: Wed Sep 29, 2004 9:31 pm    Post subject: Re: Calling functions in other files... Charlie wrote: Quote: Ok, I have three files: calc.cpp, calc.h, and ui.cpp. I would like to call a function that is located in ui.cpp from main() in calc.cpp. Both files have calc.h included, but when I tried to include ui.cpp in calc.cpp, it gave me an error due to multiple instances of the same function's. How do I call my function that is in ui.cpp from calc.cpp? Put its prototype in calc.h, don't include ui.cpp in calc.cpp (or if you do include it, don't compile and link ui.cpp as well) Back to top Default User Guest Posted: Wed Sep 29, 2004 9:38 pm    Post subject: Re: Calling functions in other files... Charlie wrote: Quote: Ok, I have three files: calc.cpp, calc.h, and ui.cpp. I would like to call a function that is located in ui.cpp from main() in calc.cpp. Both files have calc.h included, but when I tried to include ui.cpp in calc.cpp, it gave me an error due to multiple instances of the same function's. How do I call my function that is in ui.cpp from calc.cpp? Sounds like you have functions defined, not just declared, in your .h file. Don't do that. Brian Rodenborn Back to top Thomas Matthews Guest Posted: Thu Sep 30, 2004 1:31 pm    Post subject: Re: Calling functions in other files... Charlie wrote: Quote: Ok, I have three files: calc.cpp, calc.h, and ui.cpp. I would like to call a function that is located in ui.cpp from main() in calc.cpp. Both files have calc.h included, but when I tried to include ui.cpp in calc.cpp, it gave me an error due to multiple instances of the same function's. How do I call my function that is in ui.cpp from calc.cpp? When you reference (call or take the address of) a function, the compiler needs information about it, such as its return type, the number of parameters, types of parameters, etc. This can be accomplished by using a function prototype or declaration before using the function. The common guideline is to list all the declarations before the function definitions. If a function in a translation unit (i.e. cpp file) is used by other translation units, the common guideline is to place the function header into a separate file (i.e. ".h" file) and include it in each file that uses the function. In your situation, you may want to create a header file, ui.h, which contains declarations of functions that are in ui.cpp. Include this file from calc.cpp. Another common guideline is to only publish (create function declarations in files) functions that are used by other files. This will help support "encapsulation". Also declare the functions as "static". This is commonly referred to as "need to know" basis. -- Thomas Matthews C++ newsgroup welcome message: http://www.slack.net/~shiva/welcome.txt C++ Faq: http://www.parashift.com/c++-faq-lite C Faq: http://www.eskimo.com/~scs/c-faq/top.html alt.comp.lang.learn.c-c++ faq: http://www.comeaucomputing.com/learn/faq/ Other sites: http://www.josuttis.com -- C++ STL Library book Back to top charlie.lamothe@gmail.com Guest Posted: Wed Oct 06, 2004 6:14 pm    Post subject: Re: Calling functions in other files... Thanks everyone, I actually figured this out later in the day, this confirms that i'm doing it the right way :) Charlie Thomas Matthews wrote: Quote: Charlie wrote: Ok, I have three files: calc.cpp, calc.h, and ui.cpp. I would like to call a function that is located in ui.cpp from main() in calc.cpp. Both files have calc.h included, but when I tried to include ui.cpp in calc.cpp, it gave me an error due to multiple instances of the same function's. How do I call my function that is in ui.cpp from calc.cpp? When you reference (call or take the address of) a function, the compiler needs information about it, such as its return type, the number of parameters, types of parameters, etc. This can be accomplished by using a function prototype or declaration before using the function. The common guideline is to list all the declarations before the function definitions. If a function in a translation unit (i.e. cpp file) is used by other translation units, the common guideline is to place the function header into a separate file (i.e. ".h" file) and include it in each file that uses the function. In your situation, you may want to create a header file, ui.h, which contains declarations of functions that are in ui.cpp. Include this file from calc.cpp. Another common guideline is to only publish (create function declarations in files) functions that are used by other files. This will help support "encapsulation". Also declare the functions as "static". This is commonly referred to as "need to know" basis. -- Thomas Matthews C++ newsgroup welcome message: http://www.slack.net/~shiva/welcome.txt C++ Faq: http://www.parashift.com/c++-faq-lite C Faq: http://www.eskimo.com/~scs/c-faq/top.html alt.comp.lang.learn.c-c++ faq: http://www.comeaucomputing.com/learn/faq/ Other sites: http://www.josuttis.com -- C++ STL Library book 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.