OpenCV 2.3 doesn't compile, undefined reference error

Question

I'm using OpenCV in Windows 7 64bits and Netbeans 7.0. I tried to compile the next code using MinGW and cygwin but both fails with undefined references.

When I use MAT or FLANN and others I can't compile, but I'm adding all libraries (I tried only adding Debug ones, Release ones, only needed ones... but fails).

The same code in ubuntu works, but I need to compile it in windows too. I'm using the 2.3 compiled version (using CMake) and the installable one.

#include "opencv2\opencv.hpp"
#include <iostream>

using namespace std;

int main(void)
{
    cv::Mat::eye(1, 1, 0);

    return 0;
}

---

"/usr/bin/make" -f nbproject/Makefile-Release.mk QMAKE= SUBPROJECTS= .clean-conf
make[1]: Entering directory `/cygdrive/f/Proyectos/C++/OpenCV23Sandbox'
rm -f -r build/Release
rm -f dist/Release/Cygwin-Windows/opencv23sandbox.exe
make[1]: Leaving directory `/cygdrive/f/Proyectos/C++/OpenCV23Sandbox'

CLEAN SUCCESSFUL (total time: 1s)
"/usr/bin/make" -f nbproject/Makefile-Release.mk QMAKE= SUBPROJECTS= .build-conf
make[1]: Entering directory `/cygdrive/f/Proyectos/C++/OpenCV23Sandbox'
"/usr/bin/make"  -f nbproject/Makefile-Release.mk dist/Release/Cygwin-Windows/opencv23sandbox.exe
make[2]: Entering directory `/cygdrive/f/Proyectos/C++/OpenCV23Sandbox'
mkdir -p build/Release/Cygwin-Windows
rm -f build/Release/Cygwin-Windows/main.o.d
g++.exe    -c -O2 -I/cygdrive/C/OpenCV2.3/build/include -MMD -MP -MF build/Release/Cygwin-Windows/main.o.d -o build/Release/Cygwin-Windows/main.o main.cpp
mkdir -p dist/Release/Cygwin-Windows
g++.exe     -o dist/Release/Cygwin-Windows/opencv23sandbox build/Release/Cygwin-Windows/main.o -L/cygdrive/C/OpenCV2.3/build/x86/vc10/lib -lopencv_calib3d230 -lopencv_calib3d230d -lopencv_contrib230 -lopencv_contrib230d -lopencv_core230 -lopencv_core230d -lopencv_features2d230 -lopencv_features2d230d -lopencv_flann230 -lopencv_flann230d -lopencv_gpu230 -lopencv_gpu230d -lopencv_haartraining_engine -lopencv_haartraining_engined -lopencv_highgui230 -lopencv_highgui230d -lopencv_imgproc230 -lopencv_imgproc230d -lopencv_legacy230 -lopencv_legacy230d -lopencv_ml230 -lopencv_ml230d -lopencv_objdetect230 -lopencv_objdetect230d -lopencv_video230 -lopencv_video230d 
build/Release/Cygwin-Windows/main.o:main.cpp:(.text+0xac): undefined reference to `cv::Mat::eye(int, int, int)'
build/Release/Cygwin-Windows/main.o:main.cpp:(.text+0x106): undefined reference to `cv::fastFree(void*)'
build/Release/Cygwin-Windows/main.o:main.cpp:(.text+0x16f): undefined reference to `cv::fastFree(void*)'
build/Release/Cygwin-Windows/main.o:main.cpp:(.text+0x1dd): undefined reference to `cv::fastFree(void*)'
build/Release/Cygwin-Windows/main.o:main.cpp:(.text+0x1fa): undefined reference to `cv::Mat::deallocate()'
build/Release/Cygwin-Windows/main.o:main.cpp:(.text+0x20a): undefined reference to `cv::Mat::deallocate()'
build/Release/Cygwin-Windows/main.o:main.cpp:(.text+0x21a): undefined reference to `cv::Mat::deallocate()'
build/Release/Cygwin-Windows/main.o:main.cpp:(.text$_ZN2cv3MatD1Ev[cv::Mat::~Mat()]+0x66): undefined reference to `cv::Mat::deallocate()'
build/Release/Cygwin-Windows/main.o:main.cpp:(.text$_ZN2cv3MatD1Ev[cv::Mat::~Mat()]+0x5e): undefined reference to `cv::fastFree(void*)'
collect2: ld returned 1make[2]: Leaving directory `/cygdrive/f/Proyectos/C++/OpenCV23Sandbox'
make[1]: Leaving directory `/cygdrive/f/Proyectos/C++/OpenCV23Sandbox'
 exit status
make[2]: *** [dist/Release/Cygwin-Windows/opencv23sandbox.exe] Error 1
make[1]: *** [.build-conf] Error 2
make: *** [.build-impl] Error 2

BUILD FAILED (exit value 2, total time: 2s)

---

Trying with MinGW libs:

"/bin/make" -f nbproject/Makefile-Release.mk QMAKE= SUBPROJECTS= .clean-conf
make[1]: Entering directory `/f/Proyectos/C++/OpenCV23Sandbox'
rm -f -r build/Release
rm -f dist/Release/MinGW-Windows/opencv23sandbox.exe
make[1]: Leaving directory `/f/Proyectos/C++/OpenCV23Sandbox'

CLEAN SUCCESSFUL (total time: 350ms)
"/bin/make" -f nbproject/Makefile-Release.mk QMAKE= SUBPROJECTS= .build-conf
make[1]: Entering directory `/f/Proyectos/C++/OpenCV23Sandbox'
"/bin/make"  -f nbproject/Makefile-Release.mk dist/Release/MinGW-Windows/opencv23sandbox.exe
make[2]: Entering directory `/f/Proyectos/C++/OpenCV23Sandbox'
mkdir -p build/Release/MinGW-Windows
rm -f build/Release/MinGW-Windows/main.o.d
g++.exe    -c -O2 -I/C/OpenCV2.3/build/include -MMD -MP -MF build/Release/MinGW-Windows/main.o.d -o build/Release/MinGW-Windows/main.o main.cpp
mkdir -p dist/Release/MinGW-Windows
g++.exe     -o dist/Release/MinGW-Windows/opencv23sandbox build/Release/MinGW-Windows/main.o -L../OpenCV/OpenCV2.3/build/x86/mingw/lib ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_calib3d230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_contrib230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_core230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_features2d230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_flann230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_gpu230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_highgui230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_imgproc230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_legacy230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_ml230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_objdetect230.dll.a ../OpenCV/OpenCV2.3/build/x86/mingw/lib/libopencv_video230.dll.a 
build/Release/MinGW-Windows/main.o:main.cpp:(.text+0x4f): undefined reference to `cv::Mat::eye(int, int, int)'
build/Release/MinGW-Windows/main.o:main.cpp:(.text+0xac): undefined reference to `cv::fastFree(void*)'
build/Release/MinGW-Windows/main.o:main.cpp:(.text+0x11a): undefined reference to `cv::fastFree(void*)'
build/Release/MinGW-Windows/main.o:main.cpp:(.text+0x191): undefined reference to `cv::fastFree(void*)'
build/Release/MinGW-Windows/main.o:main.cpp:(.text+0x1a7): undefined reference to `cv::Mat::deallocate()'
build/Release/MinGW-Windows/main.o:main.cpp:(.text+0x1ba): undefined reference to `cv::Mat::deallocate()'
build/Release/MinGW-Windows/main.o:main.cpp:(.text+0x1ce): undefined reference to `cv::Mat::deallocate()'
build/Release/MinGW-Windows/main.o:main.cpp:(.text$_ZN2cv3MatD1Ev[cv::Mat::~Mat()]+0x74): undefined reference to `cv::Mat::deallocate()'
build/Release/MinGW-Windows/main.o:main.cpp:(.text$_ZN2cv3MatD1Ev[cv::Mat::~Mat()]+0x63): undefined reference to `cv::fastFree(void*)'
collect2: ld returned 1 exit status
make[2]: Leaving directory `/f/Proyectos/C++/OpenCV23Sandbox'
make[1]: Leaving directory `/f/Proyectos/C++/OpenCV23Sandbox'
make[2]: *** [dist/Release/MinGW-Windows/opencv23sandbox.exe] Error 1
make[1]: *** [.build-conf] Error 2
make: *** [.build-impl] Error 2

BUILD FAILED (exit value 2, total time: 1s)

or

g++.exe     -o dist/Release/MinGW-Windows/opencv23sandbox build/Release/MinGW-Windows/main.o -L../OpenCV/OpenCV2.3/build/x86/mingw/lib -lopencv_calib3d230.dll -lopencv_contrib230.dll -lopencv_core230.dll -lopencv_features2d230.dll -lopencv_flann230.dll -lopencv_gpu230.dll -lopencv_highgui230.dll -lopencv_imgproc230.dll -lopencv_legacy230.dll -lopencv_ml230.dll -lopencv_objdetect230.dll -lopencv_video230.dll 

same result.

Answer 1

I guess the Problem is that the library path points to the vc10 directory ( -L/cygdrive/C/OpenCV2.3/build/x86/vc10/lib ) instead of the mingw directory ( -L/cygdrive/C/OpenCV2.3/build/x86/mingw/lib ). The ld-linker can't find the methods because they are mangled for the vc++ "link.exe".

If you use 64 bit, then you have also link against 64-bit libs: -L/cygdrive/C/OpenCV2.3/build/x64/mingw/lib .

Answer 2

Are you using the precompiled MinGW libraries? (it appears so). I tried for a couple of days to get my project to link successfully under Code::Blocks. I was seeing the same sort of errors you describe (bad references, etc).

I finally recompiled OpenCV using the steps shown here , and all became well.

Answer 3

I have exactly the same issue. I am trying to compile my program under a 64-bit Windows 7 machine with MinGW. Here is several possibilities that may result in the problem:

1) You need to make sure OpenCV2.3/build/x64/mingw/lib is link. Be careful, don't link the project to the libs for visual studio or libs for x86.

2) Make sure the proper dll s are copied to the project directory, or have been added to PATH . For example, if you use this lib libopencv_core243.dll.a , you should make sure libopencv_core243.dll can be loaded by the project. This is not the cause of the problem. But I think it is also important to know.

3) Make sure the MinGW can compile x64 programs. This is what I use: mingw-w64 (But since mingw-w64 project is moving to mingw-w64.org it's better to use the new website). Unfortunately, the one that download from MinGW32 won't work. And the link from the official site of MinGW will bring you to a second one (MinGW32).

4) By default, MinGw may compile your project to a 32 bit program. In order to make sure it compiles for 64 bit, add this compile flag -m64 . Otherwise, if you only link the project with all the 64-bit libs, it will result in the problem as well.