new to visual C++ - "unresolved external symbol" linking errors

I've been programming for a while now, but almost exclusively in a linux environment. I've ported some code that I've been using in linux to windows for a program that I'm writing, and it all compiles cleanly, but fails whiles linking.

I'm very new to visual studio and visual c++, and I'm sure the linking problem i have is very simple to fix, but i can't get any results by fiddling around with it.

The errors i'm getting are all "unresolved external symbol" errors, and they're all of functions that I've written and are in the source files that I've ported (I was having the same linking errors with winsock functions, but i just needed to add the ws2_32.lib as a dependency in the project). All the needed source files/headerfiles are added to my project.

The code that I've ported is in a separate folder from my project's folder (which is just a simple test program for the ported code), and is also in a separate folder from their header files. I'm sure there's something else that needs to be done, but I'm not sure what or where in all of VS's menus. Any help would be really appreciated. Btw, I'm using Visual Studio .NET 2002

Are you compiling them as a mix of C/C++ source files? If that was the case, then compilation would succeed but when linking there could be problems due to mangling of function names. What are the specific errors you are getting (cut and paste them if possible)? Also explain your directory structure; all the files (headers and source code) and where they are.

Ah yeah, I forgot to mention... some are .c files, some are .cpp files.... they're all compatible with c++ (compiles and runs fine in g++. In fact, this program is a straight port of a test program that I used to test the my library in linux, with only very minor changes to get it to compile in windows).

As for the directory structure, my project's directory is in a folder called My Documents/pmc_lib_test. All the files pertaining to this library that I've made is on a separate harddrive in a folder called pmc_libs, with the header files being in this directory and the source files being in pmc_libs/win32, pmc_libs/libs/nix, and pmc_libs/c++libs (/c++libs has a couple c++ wrapper classes for the library, which was written in C. The wrapper classes are also being used in the VS project).

Also, not sure if this matters, but the include lines in the source files reference the header file's location relatively, (#include "../pmc.h", for example).

Here is the cut and paste of the error log:

Code:

    Linking...
pmc_lib_test.obj : error LNK2019: unresolved external symbol "int __cdecl pmc_addtlv(struct pmcMsg *,unsigned short,unsigned short,void *)" (?pmc_addtlv@@YAHPAUpmcMsg@@GGPAX@Z) referenced in function _main
pmc_wrapper.obj : error LNK2001: unresolved external symbol "int __cdecl pmc_addtlv(struct pmcMsg *,unsigned short,unsigned short,void *)" (?pmc_addtlv@@YAHPAUpmcMsg@@GGPAX@Z)
pmc_lib_test.obj : error LNK2019: unresolved external symbol "struct pmcMsg * __cdecl pmc_createmsg(struct pmcMsg * *,unsigned short,unsigned short,unsigned short)" (?pmc_createmsg@@YAPAUpmcMsg@@PAPAU1@GGG@Z) referenced in function _main
pmc_wrapper.obj : error LNK2001: unresolved external symbol "struct pmcMsg * __cdecl pmc_createmsg(struct pmcMsg * *,unsigned short,unsigned short,unsigned short)" (?pmc_createmsg@@YAPAUpmcMsg@@PAPAU1@GGG@Z)
pmc_lib_test.obj : error LNK2019: unresolved external symbol "int __cdecl initwinsock(void)" (?initwinsock@@YAHXZ) referenced in function _main
pmc_wrapper.obj : error LNK2019: unresolved external symbol "int __cdecl pmc_sendmsg(int,struct pmcMsg * *,char)" (?pmc_sendmsg@@YAHHPAPAUpmcMsg@@D@Z) referenced in function "public: int __thiscall CPMCMsg::Send(int)" (?Send@CPMCMsg@@QAEHH@Z)
pmc_wrapper.obj : error LNK2019: unresolved external symbol "struct rpmcMsg * __cdecl pmc_recvmsg(int)" (?pmc_recvmsg@@YAPAUrpmcMsg@@H@Z) referenced in function "public: int __thiscall CPMCMsg::Recv(int)" (?Recv@CPMCMsg@@QAEHH@Z)
.\Debug/pmc_lib_test.exe : fatal error LNK1120: 5 unresolved externals

pmc_lib_test is the VS project, and pmc_wrapper is the source that contains the c++ wrapper classes.

Here is my command line log:

Code:

    Creating temporary file "C:\DOCUME~1\Matt\LOCALS~1\Temp\RSP000001.rsp" with contents
[
/OUT:".\Debug/pmc_lib_test.exe" /INCREMENTAL /NOLOGO /DEBUG /PDB:".\Debug/pmc_lib_test.pdb" /SUBSYSTEM:CONSOLE /MACHINE:I386 odbc32.lib odbccp32.lib ws2_32.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib
"Debug\StdAfx.obj"
"Debug\pmc_lib_test.obj"
"Debug\pmc_w32.obj"
"Debug\pmc_wrapper.obj"
"Debug\srv_general_w32.obj"
]
Creating command line "link.exe @C:\DOCUME~1\Matt\LOCALS~1\Temp\RSP000001.rsp"

Any thoughts? Thanks for the help and quick reply

Would this thread better fit in the windows programming forum? If so, could a moderator move it there please?

First of all it has nothing to do with the location of the headers because compling seems to work fine. The errors are linker errors.
So I guess you have to link to some library that contain all these functions.
Kurt

> The code that I've ported is in a separate folder from my project's folder
The "simple" answer is to just add all your "pmc library" source code to your test project so that everything compiles together.

The "better" answer is to create a library project in your pmc library folder, compile that up as a library. Then in your test project, add appropriate links to "pmc.h" and "pmc.lib" in the same way that you did for winsock library.

Alright, I thought that might be the case. Not a big deal, just a bit of a nuisance since the pmc source will still constantly need to be edited and recompiled. Thanks for the help

Well, the problem turned out to be the mangling of my C function names... all I had to do was export the C functions using

Code:

#ifdef __cplusplus
extern "C" {  
#endif	

//Declare C functions here

#ifdef __cplusplus
}
#endif

in my header files, and it all compiles and links fine now. Stupid mistake =/ Hopefully this helps someone having the same problem, though

Hiya, not sure if you're still checking this thread, but i seem to be having virtually the same problem as you were. i tried what you suggested and it reduced the length of the linker errors, but they still show up except instead of looking like:

Code:

SCFfunction.obj : error LNK2001: unresolved external symbol "int __cdecl fwrite_scf(struct Scf *,struct _iobuf *)" (?fwrite_scf@@YAHPAUScf@@PAU_iobuf@@@Z)

they have been shortened to:

Code:

SCFfunction.obj : error LNK2001: unresolved external symbol _fwrite_scf

now it just looks like i've simply forgotten to include a library, but i didn't change anything else. did you see anything like that at all? it's probably just something really simple that's eluding me.

cheers