unresolved external symbol - Error using Matlab API - matlab

Question

I'm trying to read a .mat-file in C++ with MSVS 2008 but when building a simple program I get the following error:
1>ex3.obj : error LNK2019: unresolved external symbol _matClose referenced in function _main
1>ex3.obj : error LNK2019: unresolved external symbol _matOpen referenced in function _main
I've researched Google as well and it seems that the compiler can't link to the libraries needed for using this functions (matOpen and matClose). I never used an external library before but I tried everything I found in Google to add the Matlab libraries. I did the following:
TOOLS --> Options --> Projects and Solutions --> VC++ Directories --> Show directories for: include files --> then I added the path of the matlab include directory --> C:\Program Files\MATLAB\extern\include
I did the same with the library files: C:\Program Files\MATLAB\extern\lib\win64\microsoft
I also did that for the project:
Right click on the project --> Properties --> Configuration Properties --> C/C++ --> General --> Additional Include Directories --> and added "C:\Program Files\MATLAB\extern\include\win64"
Then I did the same at Linker --> General --> Additional Library Directories --> and added "C:\Program Files\MATLAB\extern\lib\win64\microsoft"
So I really don't know where the problem is. Here is the source code I'm trying to build:
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <mat.h>
int main(int argc, char *argv[])
{
const char *file = "mozart_part1.mat";
MATFile *pmat;
pmat = matOpen(file, "r");
if(pmat == NULL)
{
std::cout << "Error: could not open MAT-file!";
return(1);
}
matClose(pmat);
}
Can you see or guess any mistakes I made

Answer 1

Take a look here.
Go through the steps.
What I think you've missed is step 7:
7.Locate the .lib files for the compiler you are using under matlabroot\extern\lib\win32\microsoft or matlabroot\extern\lib\win64\microsoft. Under Linker Input properties, add libmx.lib, libmex.lib, and libmat.lib as additional dependencies.
Edit:
Both Matlab and Visual C++ should be either 32bit or 64bit. There are two options:
Find these 3 lib files from another Matlab which is 32bit. Direct your linker there instead.
Make your Visual C++ 64bit. See here how it's done.
Solution:
What eventually worked was option 2, using this link with instructions.

Answer 2

I solved the Problem!
#Michael Litvin: you were right! I didn't know that you have to switch MSVS 2008 to x64 platform.
As the Matlab libraries are provided as x64 binaries you have to switch your MSVS compiler to x64 as well. I followed these steps to do that: http://software.intel.com/en-us/articles/configuring-microsoft-visual-studio-for-64-bit-applications/
Thanks for you help!