BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Unresolved external          BorlandTalk.com Forum Index -> C++ Builder (Language C++) View previous topic :: View next topic   Author Message LMario Guest Posted: Fri Mar 11, 2005 9:13 pm    Post subject: Unresolved external I have a program which calls a C function from a separate source file but I keep getting unresolved external errors. When I add CPP functions (in a sparate file) to my program I don't have any problems. Are there differences to incorporte C o CPP functions to a CBuilder proyect. I can't simply rename my C file to CPP because then when I compile I receive compilation errors. Back to top Helmut Giese Guest Posted: Fri Mar 11, 2005 9:33 pm    Post subject: Re: Unresolved external On Fri, 11 Mar 2005 15:13:42 -0600, "LMario" <lefalme (AT) prodigy (DOT) net.mx> wrote: Quote: I have a program which calls a C function from a separate source file but I keep getting unresolved external errors. When I add CPP functions (in a sparate file) to my program I don't have any problems. Are there differences to incorporte C o CPP functions to a CBuilder proyect. I can't simply rename my C file to CPP because then when I compile I receive compilation errors. While what Chris said is certainly true, may I add that you should maybe search for the root of the problem? Actually, I usually advise people to compile even their C programs as C++, because this lets the compiler sometimes find bugs. In other words: If I had a C program which is not acceptable as a C++ program I would have a very, very close look as to why - chances are high, that I am doing something which I shouldn't do. Of course just my 0.02. Best regards Helmut Giese Back to top Chris Uzdavinis (TeamB) Guest Posted: Fri Mar 11, 2005 10:01 pm    Post subject: Re: Unresolved external [email]hgiese (AT) ratiosoft (DOT) com[/email] (Helmut Giese) writes: Quote: While what Chris said is certainly true, may I add that you should maybe search for the root of the problem? Actually, I usually advise people to compile even their C programs as C++, because this lets the compiler sometimes find bugs. In other words: If I had a C program which is not acceptable as a C++ program I would have a very, very close look as to why - chances are high, that I am doing something which I shouldn't do. Of course just my 0.02. I agree that a C++ compiler can potentially catch bugs that a C compiler permits. Or, alternately, at least catches things that are questionable or not portable. (Sometimes C code ends up pasted in a C++ file afterall.) However, if the full file is entirely C, the production code probably should be built with a C compiler. First of all, at least with g++ 3.2, we have some C code that runs faster when compiled as C than as C++. Second, other languags may use C functions but can't use C++ functions. Maybe that's important. -- Chris (TeamB); Back to top Duane Hebert Guest Posted: Fri Mar 11, 2005 10:13 pm    Post subject: Re: Unresolved external "Chris Uzdavinis (TeamB)" <chris (AT) uzdavinis (DOT) com> wrote Quote: hgiese (AT) ratiosoft (DOT) com (Helmut Giese) writes: While what Chris said is certainly true, may I add that you should maybe search for the root of the problem? Actually, I usually advise people to compile even their C programs as C++, because this lets the compiler sometimes find bugs. In other words: If I had a C program which is not acceptable as a C++ program I would have a very, very close look as to why - chances are high, that I am doing something which I shouldn't do. Of course just my 0.02. I agree that a C++ compiler can potentially catch bugs that a C compiler permits. Or, alternately, at least catches things that are questionable or not portable. (Sometimes C code ends up pasted in a C++ file afterall.) However, if the full file is entirely C, the production code probably should be built with a C compiler. First of all, at least with g++ 3.2, we have some C code that runs faster when compiled as C than as C++. Second, other languags may use C functions but can't use C++ functions. Maybe that's important. It's also possible that the OP has a library compiled in C. In this case, the extern c stuff is necessary. Back to top Helmut Giese Guest Posted: Fri Mar 11, 2005 10:17 pm    Post subject: Re: Unresolved external On Fri, 11 Mar 2005 17:01:36 -0500, Chris Uzdavinis (TeamB) <chris (AT) uzdavinis (DOT) com> wrote: Hi Chris, you're way ahead of me Quote: I agree that a C++ compiler can potentially catch bugs that a C compiler permits. Or, alternately, at least catches things that are questionable or not portable. (Sometimes C code ends up pasted in a C++ file afterall.) However, if the full file is entirely C, the production code probably should be built with a C compiler. First of all, at least with g++ 3.2, we have some C code that runs faster when compiled as C than as C++. Second, other languags may use C functions but can't use C++ functions. Maybe that's important. Well, even if this is the case (and only the OP can tell us) my advice would still be: If C code does not compile as C++ code, I would have a very close look at the errors the C++ compiler identifies. Then, in a second step, I'd switch back to C to - maybe - get more performant code, offer a C-like interface or whatever. Best regards Helmut Giese Back to top LMario Guest Posted: Fri Mar 11, 2005 11:00 pm    Post subject: Re: Unresolved external Thanks, now all is working. "Chris Uzdavinis (TeamB)" <chris (AT) uzdavinis (DOT) com> wrote Quote: "LMario" <lefalme (AT) prodigy (DOT) net.mx> writes: I have a program which calls a C function from a separate source file but I keep getting unresolved external errors. When I add CPP functions (in a sparate file) to my program I don't have any problems. Are there differences to incorporte C o CPP functions to a CBuilder proyect. I can't simply rename my C file to CPP because then when I compile I receive compilation errors. When you include the header that prototyptes the C functions, be sure to tell the compiler that the contents should have C linkage. extern "C" { #include "mychdr.h" } The reason is that when you compile the C++ program that includes this header, in that file the names get mangled because the functions are thought to be C++ functions. But when you compile the .c file itself, the names are not mangled since it's not a c++ compiler. Thus, the mismatch is that the names exported/imported do not mesh. -- Chris (TeamB); Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> C++ Builder (Language C++) All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  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.