Couldn't link opencv with qt creator , this error happens

[Being friendzoned sucks]

Hello,

I've been trying to solve this since yesterday with no luck,

first I downloaded the latest version of opencv , it came with it two folders , one is source and one is build I assumed build folder is the precompiled folder which is what I want, anyways I did this in the pro file:

INCLUDEPATH += C:/opencv/build/include
LIBS +=-LC:/opencv/build/x86/vc11/staticlib
CONFIG(debug, debug|release){
LIBS +=-lopencv_core249\
LIBS +=-lopencv_core249d\
LIBS +=-lopencv_highgui249\
LIBS +=-lopencv_highgui249d\
}

INCLUDEPATH += C:/opencv/build/include
LIBS +=-LC:/opencv/build/x86/vc11/staticlib
CONFIG(debug, debug|release){
LIBS +=-lopencv_core249\
LIBS +=-lopencv_core249d\
LIBS +=-lopencv_highgui249\
LIBS +=-lopencv_highgui249d\
}

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and it gives me this error:

:-1: error: LNK1104: cannot open file '+=-lopencv_core249d.obj'

:-1: error: LNK1104: cannot open file '+=-lopencv_core249d.obj'

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when I delete
LIBS +=-lopencv_core249d\

it gives me the same error except it's for the highgui249d file.

[Zlatomir]

The -l lib name option needs to be on the same line as the -L so you need a \, and also the debug/release are not supposed to be linked together, so the syntax should become something like:

CONFIG( debug, debug|release ) {
#debug libs
        LIBS +=-LC:/opencv/build/x86/vc11/staticlib\
        -lopencv_core246d\
        -lopencv_highgui246d
}
else {
#release libs
        LIBS +=-LC:/opencv/build/x86/vc11/staticlib\
        -lopencv_core246\
        -lopencv_highgui246
}

CONFIG( debug, debug|release ) {
#debug libs
        LIBS +=-LC:/opencv/build/x86/vc11/staticlib\
        -lopencv_core246d\
        -lopencv_highgui246d
}
else {
#release libs
        LIBS +=-LC:/opencv/build/x86/vc11/staticlib\
        -lopencv_core246\
        -lopencv_highgui246
}

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[Being friendzoned sucks]

The -l lib name option needs to be on the same line as the -L so you need a \, and also the debug/release are not supposed to be linked together, so the syntax should become something like:

CONFIG( debug, debug|release ) {
#debug libs
        LIBS += -LLIBS +=-LC:/opencv/build/x86/vc11/staticlib\
        -lopencv_core246d\
        -lopencv_highgui246d
}
else {
#release libs
        LIBS += -LLIBS +=-LC:/opencv/build/x86/vc11/staticlib\
        -lopencv_core246\
        -lopencv_highgui246
}

CONFIG( debug, debug|release ) {
#debug libs
        LIBS += -LLIBS +=-LC:/opencv/build/x86/vc11/staticlib\
        -lopencv_core246d\
        -lopencv_highgui246d
}
else {
#release libs
        LIBS += -LLIBS +=-LC:/opencv/build/x86/vc11/staticlib\
        -lopencv_core246\
        -lopencv_highgui246
}

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well thanks buddy , now I have a new problem:

LNK1181: cannot open input file 'opencv_core246.lib'

when I compile in release mode and when I compile in debug mode it shows the same problem except for the debug file:

LNK1181: cannot open input file 'opencv_core246d.lib'

[Zlatomir]

My bad, sorry, some copy/paste errors, i corrected the error in my previous post, and also you seem to have the 2.49 version of opencv (you can check the file names in that lib folder), so the code becomes:

CONFIG( debug, debug|release ) {
    #debug libs
    LIBS +=-LC:/opencv/build/x86/vc11/staticlib\
    -lopencv_core249d\
    -lopencv_highgui249d
    }
    else {
    #release libs
    LIBS +=-LC:/opencv/build/x86/vc11/staticlib\
    -lopencv_core249\
    -lopencv_highgui249
    }

CONFIG( debug, debug|release ) {
    #debug libs
    LIBS +=-LC:/opencv/build/x86/vc11/staticlib\
    -lopencv_core249d\
    -lopencv_highgui249d
    }
    else {
    #release libs
    LIBS +=-LC:/opencv/build/x86/vc11/staticlib\
    -lopencv_core249\
    -lopencv_highgui249
    }

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LE: don't forget to run qmake after you modify the .pro file.

[Being friendzoned sucks]

Yeah I fixed the copy thing before using it

but I'm stupid enough to forget about changing the names to the new version names..

anyways they're still some problems

first I added these to my pro file:

INCLUDEPATH += C:/opencv249/build/include/
CONFIG( debug, debug|release ) {
#debug libs
        LIBS +=-LC:/opencv249/build/x64/vc11/staticlib\
        -lopencv_core249d\
        -lopencv_highgui249d
}
else {
#release libs
        LIBS +=-LC:/opencv249/build/x64/vc11/staticlib\
        -lopencv_core249\
        -lopencv_highgui249
}

INCLUDEPATH += C:/opencv249/build/include/
CONFIG( debug, debug|release ) {
#debug libs
        LIBS +=-LC:/opencv249/build/x64/vc11/staticlib\
        -lopencv_core249d\
        -lopencv_highgui249d
}
else {
#release libs
        LIBS +=-LC:/opencv249/build/x64/vc11/staticlib\
        -lopencv_core249\
        -lopencv_highgui249
}

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second here is the includes + code

#include<opencv/cv.h>
#include<opencv/highgui.h>
 
void MainWindow::showimage1(){
    IplImage*img=cvLoadImage("C:\\Users\\myuser\\QT\\build-CaptureTools-Unnamed-Debug\\Fri May 2 2014_3039.png");
    cvNamedWindow("example",CV_WINDOW_AUTOSIZE);
    cvShowImage("example",img);
    cvWaitKey(0);
    cvReleaseImage(&img);
    cvDestroyWindow("example");
 
}

#include<opencv/cv.h>
#include<opencv/highgui.h>

void MainWindow::showimage1(){
    IplImage*img=cvLoadImage("C:\\Users\\myuser\\QT\\build-CaptureTools-Unnamed-Debug\\Fri May 2 2014_3039.png");
    cvNamedWindow("example",CV_WINDOW_AUTOSIZE);
    cvShowImage("example",img);
    cvWaitKey(0);
    cvReleaseImage(&img);
    cvDestroyWindow("example");

}

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------------------------------------------

first I'll start with the notifications that it shows in the issues section along with the errors:

C:\opencv249\build\include\opencv2\flann\logger.h:66: warning: C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
 
C:\opencv249\build\include\opencv2\flann\logger.h:66: warning: C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
 
C:\opencv249\build\include\opencv2\flann\logger.h:66: warning: C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.

C:\opencv249\build\include\opencv2\flann\logger.h:66: warning: C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.

C:\opencv249\build\include\opencv2\flann\logger.h:66: warning: C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.

C:\opencv249\build\include\opencv2\flann\logger.h:66: warning: C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.

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-----------------------------------------------------

the errors:

mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvReleaseImage referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)
 
mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvNamedWindow referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)
 
mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvShowImage referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)
 
mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvDestroyWindow referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)
 
mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvLoadImage referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)
 
mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvWaitKey referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)
 
debug\CaptureTools.exe:-1: error: LNK1120: 6 unresolved externals

mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvReleaseImage referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)

mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvNamedWindow referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)

mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvShowImage referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)

mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvDestroyWindow referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)

mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvLoadImage referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)

mainwindow.obj:-1: error: LNK2019: unresolved external symbol _cvWaitKey referenced in function "public: void __thiscall MainWindow::showimage1(void)" (?showimage1@MainWindow@@QAEXXZ)

debug\CaptureTools.exe:-1: error: LNK1120: 6 unresolved externals

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[Zlatomir]

Are you trying to build using the same compiler as opencv version? (from the opencv path is seems to be vc11, that means Visual Studio 2012)