Type undefined reference to `cv::fastFree(void*)'

Question

I started the tutorial for opencv 2.4.7 on Win8, latest MinGW, and Eclipse Kepler R1, CDT. C++ Compiler includes are referencing to [path-to-opencv]\open247\build\include.

in the MinGW C++ Linker I add the library path [path-to-opencv]\open247\build\x64\vc11\lib. The vc11 directory contains libraries for VisualStudio from what I've read. Is that still okay to compile them with MinGW?

I added the core and highgui library for this sample (I don't think we need more than those).

However, for this simple idle code below, I provoke the following compilation error.

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>

using namespace cv;
using namespace std;

int main(){
    Mat image;
}

The error on compilation is:

Description Resource    Path    Location    Type
undefined reference to `cv::fastFree(void*)'    FirstOpenCV     line 278, external location: C:\Users\John\Documents\Software\opencv247\build\include\opencv2\core\mat.hpp  C/C++ Problem

What's the reason for this?

If I add

namedWindow("testWindow", 1);

I even get this error

Description Resource    Path    Location    Type
undefined reference to `cv::namedWindow(std::string const&, int)'   main.cpp    /FirstOpenCV/src    line 23 C/C++ Problem

Answer 1

Have you link correctly your library?

-lopencv_core
-lopencv_highgui
-L<opencv_library_path>

The libraries have to be specified after the source file on the compiler/linker command line. (The linker keeps track of unresolved symbols, and resolves them via later command-line arguments.)