undefined reference to `cvCreateCameraCapture'

[musa_yilmaz]

hi, i am new at qt, i installed opencv, and i want to make i simple example like capturing a frame from webcam. i wrote the first line but it gave error. so i cant continue.

codes in my main class is :
#include <QtGui/QApplication>
#include "mainwindow.h"
#include "opencv/cv.h"
#include "opencv/highgui.h"
#include "opencv/cxcore.h"

CvCapture* myCap;
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
myCap = cvCaptureFromCAM(0);
return a.exec();
}
it gives everytime same error what should i do ?
"undefined reference to `cvCreateCameraCapture'"

[ComaWhite]

You need to link to the OpenCV libraries.

[musa_yilmaz]

hmm thanks, how can i do it ?

[Lykurg]

Use your pro file! Something like that (found through simple google-ing):

INCLUDEPATH += "C:\Program Files\OpenCV\cxcore\include" \
"C:\Program Files\OpenCV\cv\include" \
"C:\Program Files\OpenCV\cvaux\include" \
"C:\Program Files\OpenCV\otherlibs\highgui" \
"C:\Program Files\OpenCV\cxcore\include"
win32:LIBS += -L"C:\Program Files\OpenCV\lib"
LIBS += -lcv \
-lcvaux \
-lhighgui \
-lcxcore

INCLUDEPATH += "C:\Program Files\OpenCV\cxcore\include" \
"C:\Program Files\OpenCV\cv\include" \
"C:\Program Files\OpenCV\cvaux\include" \
"C:\Program Files\OpenCV\otherlibs\highgui" \
"C:\Program Files\OpenCV\cxcore\include"
win32:LIBS += -L"C:\Program Files\OpenCV\lib"
LIBS += -lcv \
-lcvaux \
-lhighgui \
-lcxcore

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[musa_yilmaz]

thanx my friend, is it possible to be made automaticly ?

[Lykurg]

? Don't understand you. What should be automatic?

[musa_yilmaz]

can Qt add this parameters automaticly or every project we have to declare them manually ?

[Lykurg]

No, you have to add these lines one time at the pro file for every project you start. There is no automatic way to do it.
And I don't know your definition of "work" but this takes only 2 seconds and if you don't start a new project every 5 seconds, It's no big deal.

[spirit]

you should add new libs manually in pro-file.

[musa_yilmaz]

thanks i see no problem any more

[hezbon]

Am using linux and i have downloaded Opencv2.2.0 and i have same problem i cannot see the lib folder in my opencv please any assistance

Use your pro file! Something like that (found through simple google-ing):

INCLUDEPATH += "C:\Program Files\OpenCV\cxcore\include" \
"C:\Program Files\OpenCV\cv\include" \
"C:\Program Files\OpenCV\cvaux\include" \
"C:\Program Files\OpenCV\otherlibs\highgui" \
"C:\Program Files\OpenCV\cxcore\include"
win32:LIBS += -L"C:\Program Files\OpenCV\lib"
LIBS += -lcv \
-lcvaux \
-lhighgui \
-lcxcore

INCLUDEPATH += "C:\Program Files\OpenCV\cxcore\include" \
"C:\Program Files\OpenCV\cv\include" \
"C:\Program Files\OpenCV\cvaux\include" \
"C:\Program Files\OpenCV\otherlibs\highgui" \
"C:\Program Files\OpenCV\cxcore\include"
win32:LIBS += -L"C:\Program Files\OpenCV\lib"
LIBS += -lcv \
-lcvaux \
-lhighgui \
-lcxcore

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[spirit]

Did you build it (sources) or you downloaded already built version (binaries)?