Another noob header question

[cypherzero]

Using this header file (mstring.h) for a class defined in a seperate file (mstring.cpp) I recieve 8 'unresolved external symbol' errors when trying to use the class in my main source file (main.cpp). Could someone please tell me if I am making yet another newbie mistake? I'm sure this has always worked in the past!

///////////////
// mstring.h //
///////////////
#include <string>
 
class MSTRING : public std::string
    {
    public:
        MSTRING();
        MSTRING(std::string copyfrom);
        MSTRING(char* charpos);
        MSTRING (unsigned long i, int base = 10);
        bool contains(MSTRING txt);
        MSTRING ucase();
        MSTRING lcase();
        MSTRING subst(MSTRING f, MSTRING r);
    };
 
/////////////
// ERRORS: //
/////////////
main.obj : error LNK2019: unresolved external symbol "public: bool __thiscall MSTRING::contains(class MSTRING)" (?contains@MSTRING@@QAE_NV1@@Z) referenced in function "bool __cdecl testfilter(class MSTRING)" (?testfilter@@YA_NVMSTRING@@@Z)
main.obj : error LNK2019: unresolved external symbol "public: __thiscall MSTRING::MSTRING(char *)" (??0MSTRING@@QAE@PAD@Z) referenced in function "void __cdecl out_memstring(char *)" (?out_memstring@@YAXPAD@Z)
main.obj : error LNK2019: unresolved external symbol "public: __thiscall MSTRING::MSTRING(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (??0MSTRING@@QAE@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) referenced in function "class MSTRING __cdecl get_windowinfo(struct HWND__ *,int)" (?get_windowinfo@@YA?AVMSTRING@@PAUHWND__@@H@Z)
main.obj : error LNK2019: unresolved external symbol "public: class MSTRING __thiscall MSTRING::lcase(void)" (?lcase@MSTRING@@QAE?AV1@XZ) referenced in function "void __cdecl autofinds(void)" (?autofinds@@YAXXZ)
main.obj : error LNK2019: unresolved external symbol "public: __thiscall MSTRING::MSTRING(void)" (??0MSTRING@@QAE@XZ) referenced in function "void __cdecl autofinds(void)" (?autofinds@@YAXXZ)
main.obj : error LNK2019: unresolved external symbol "public: __thiscall MSTRING::MSTRING(unsigned long,int)" (??0MSTRING@@QAE@KH@Z) referenced in function "void __cdecl out_windowinfo(struct HWND__ *)" (?out_windowinfo@@YAXPAUHWND__@@@Z)
main.obj : error LNK2019: unresolved external symbol "public: class MSTRING __thiscall MSTRING::subst(class MSTRING,class MSTRING)" (?subst@MSTRING@@QAE?AV1@V1@0@Z) referenced in function _main
 
 

[Hypnotik]

I think you need a destructor function for your mstring class.

J

[cypherzero]

Tried it, I get the same errors =o(

[Benny the Guard]

The problem is this is only a header, it does not contain the definitions for the class, just declares the interface. So you have to do one of two things to make the code accessible.

1. If this code is in a separate library already, you have to configure your program to link against that DLL (Linux/Unix usually do not have this problem as they can find the proper library usually).

2. If its not already in a library the owner of the mstring.h file should have provided you with a mstring.cpp file with this. You would then add this file into your project as well, so it compiled your code and their code into a single executable.

As it stands now it cannot find any of the code for the class.