'unresolved external symbol' error when li

Question

I build the OpenCV 3.0 from source. And with the contrib repo for some extra modules. And I manually setup my VS2013 project to use the generated lib files.

My code is simple for now:

#include "opencv2\core\core.hpp"
#include "opencv2\imgcodecs\imgcodecs.hpp"

int _tmain(int argc, _TCHAR* argv[])
{
    cv::Mat image = cv::imread("img.jpg");
    return 0;
}

But it gave me these errors when in VS 2013 community version:

I see similar thread, they said it is caused by the x86/x64 issue. But My project is already x86. And the OpenCV I built is also targeting x86 (see below). What reason could it be?

ADD 1

The OpenCV 3.0 INSTALL project generates the following lib directory:

So it is indeed a x86 one.

My lib path is configured to the above path:

And I added all the *d.lib files.

And below is my VC project's Configuration Manager

So it is indeed x86, too.

Where could be wrong?

ADD 2

I manually searched for the fastFree() function. It is defined in the opencv_core300d.lib file. I use the dumpbin /symbols command to check the symbols. And I find its name is mangled exactly as fastFree@cv@@YAXPAX@Z. So why it cannot be found?

Answer 1

Here the steps to use OpenCV 3.0.0 with precompiled libs, for a C++ project that links OpenCV statically, in Windows (tested with Windows 8.1) and Visual Studio (tested with Visual Studio 2013) to run this program:

#include <opencv2\opencv.hpp>
using namespace cv;

int main()
{
    Mat3b img = imread("path_to_image");
    imshow("img", img);
    waitKey();
    return 0;
}

1. Download from http://opencv.org/downloads.html
2. Extract
3. Let's call OPENCV_DIR the dir containing:
   • build
   • source
4. Create an empty project:
   • New Project -> Visual C++ -> Empty Project
5. Add a cpp file (say Start.cpp) that will contain your main function (e.g. the snippet above)
6. Configuration DEBUG
7. Add include and lib directories:
   • Configuration Properties -> VC++ Directories
   • Include Directories: add OPENCV_DIR\build\include
   • Library Directories: add OPENCV_DIR\build\x86\vc12\staticlib

8. Add required libs (the following are good for this simple example, you should add more if you need other functionalities):

   • opencv_core300d.lib
   • opencv_highgui300d.lib
   • opencv_imgproc300d.lib
   • opencv_hal300d.lib
   • opencv_imgcodecs300d.lib
   • libjpegd.lib;
   • libpngd.lib
   • libjasperd.lib
   • IlmImfd.lib
   • libtiffd.lib
   • libwebpd.lib
   • zlibd.lib
   • ippicvmt.lib
   • %(AdditionalDependencies)

9. Configuration Properties -> C/C++ -> Code Generation -> Runtime Library

   • Set to Multi-threaded Debug (/MTd)

10. For a RELEASE build, you need to do steps from 6 to 9 in release mode, adding libs without the trailing "d" in step 8, and Multi threaded (/MT) in step 9.

11. Enjoy!

As a bonus, I also recommend to install Image Watch extension for Visual Studio. Very very useful for debugging your Mats!

Answer 2

Obviously you are linking mismatched libs. Depending on your setup, either change your project into 64 bit by 'Project Properties -> Configuration Manager', or change your lib path to point to x86 libs. (btw, since I'm a new user, I cannot comment, so I have to write it as an answer here)