MATLAB: C++ error when using MatLab dll: one or more multiply defined symbols found

matlab dllmatlab to cmcr

Hi,
I am trying to use a MatLab function in C++ by using the MCR (MatLab Compiler Runtime). However, I get an error when I call the function from C++.
This is the output when I try to build:
1>------ Build started: Project: MatLab DLL Test 2, Configuration: Debug x64 ------
1>Compiling...
1>main.cpp
1>libfoo.cpp
1>Generating Code...
1>Linking...
1>libfoo.lib(libfoo.dll) : error LNK2005: "void __cdecl foo(int,class mwArray &,class mwArray const &)" (?foo@@YAXHAEAVmwArray@@AEBV1@@Z) already defined in libfoo.obj
1>libfoo.lib(libfoo.dll) : error LNK2005: "void __cdecl foo(int,class mwArray &,class mwArray const &)" (?foo@@YAXHAEAVmwArray@@AEBV1@@Z) already defined in libfoo.obj
1>C:\Users\fmarsman\Documents\Visual Studio 2008\Projects\Project1\MatLab DLL Test 2\x64\Debug\MatLab DLL Test 2.exe : fatal error LNK1169: one or more multiply defined symbols found
1>Build log was saved at "file://c:\Users\fmarsman\Documents\Visual Studio 2008\Projects\Project1\MatLab DLL Test 2\MatLab DLL Test 2\x64\Debug\BuildLog.htm"
1>MatLab DLL Test 2 - 3 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
This is what I have done:
  • I created the .m file foo.m:
function y = foo(x)
y = x + 1;
  • In command prompt, I executed:
mcc –W cpplib:libfoo –T link:lib foo
  • This created libfoo.lib, libfoo.h libfoo.dll and libfoo.cpp
  • Next, I created a project in MS Visual Studio 2008. I added libfoo.cpp to 'Source Files' and libfoo.h to 'Header Files'.I added three directories to Configuration Properties -> C/C++ -> General -> Additional Include Directories:
C:\Users\fmarsman\Documents\MATLAB\DLL Test 2 (the folder where all the libfoo.* are)
C:\Program Files\MATLAB\MATLAB Compiler Runtime\v82\extern\lib\win64\microsoft (for the mclmcrrt.lib)
C:\MATLAB\R2013b\extern\include (for mclmcrrt.h)
  • To Linker -> Input -> Additional Dependencies I added:
"C:\Program Files\MATLAB\MATLAB Compiler Runtime\v82\extern\lib\win64\microsoft\mclmcrrt.lib"
"C:\Users\fmarsman\Documents\MATLAB\DLL Test 2\libfoo.lib"
My source code:
#include <iostream>
#include <mclmcrrt.h>
#include <mclcppclass.h>
#include <libfoo.h>
using namespace std;
int main( ) {
mclInitializeApplication(NULL,0);
libfooInitialize( );
mwArray y(1, 1, mxDOUBLE_CLASS);
y = 3.0;
const mwArray x = y.Clone();
foo(1,y,x);
mclTerminateApplication( );
libfooTerminate( );
return 0;
} // main
I've been trying to find a solution all day but without success. I really hope someone can help me with this.

Best Answer

I've got the answer on stackoverflow.com; the only thing I needed to do was removing libfoo.cpp from my project.