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WebCam using error with opencv and c++

asked 2015-03-27 13:14:04 -0500

namiqaliyev gravatar image

There is a c++ code for capturing from webcam. This is a code.

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

using namespace std;
using namespace cv;

int main(int argc, const char *argv[])
    VideoCapture vid(0);
        cout<<"Camera could not load..."<<endl;
        return -1;
        Mat frame;
        bool ctrl =;
        if(waitKey(0) == 27){
            cout<<"The app is ended..."<<endl;
    return 0;

But when I try to compile it : g++ webcam.cpp -lopencv_core -lopencv_highgui it raises an error

/tmp/ccApncrK.o: In function `main':
webcam.cpp:(.text+0x1a): undefined reference to `cv::VideoCapture::VideoCapture(int)'
webcam.cpp:(.text+0x26): undefined reference to `cv::VideoCapture::isOpened() const'
webcam.cpp:(.text+0xc3): undefined reference to `cv::VideoCapture::read(cv::_OutputArray const&)'
webcam.cpp:(.text+0x195): undefined reference to `cv::VideoCapture::~VideoCapture()'
webcam.cpp:(.text+0x1f7): undefined reference to `cv::VideoCapture::~VideoCapture()'
collect2: error: ld returned 1 exit status

Can you help me, please. PS. (I am using Ubuntu...)

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similar problem, as in your other question, the libs in opencv 2.4 and 3.0 differ. in this case you'll additionally need -lopencv_videoio

berak gravatar imageberak ( 2015-03-27 13:47:39 -0500 )edit

@jayshree, -- please do not post answer, if you do not have any.

berak gravatar imageberak ( 2016-10-07 11:01:05 -0500 )edit

sorry. I did not see your comment

jayshree gravatar imagejayshree ( 2016-10-07 12:06:38 -0500 )edit

Hi, give the path of the opencv library with -L flag.

Akhilesh gravatar imageAkhilesh ( 2016-12-23 04:07:13 -0500 )edit

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answered 2016-08-01 05:38:02 -0500

Link following libraries and it should work g++ webcam.cpp -o objDetection -lopencv_core -lopencv_imgproc -lopencv_objdetect -lopencv_highgui

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sorry, but this is incorrect.

for opencv3 you'll need -lopencv_videoio (for the webcam), also objdetect is only nessecary for cascade detection or similar.

berak gravatar imageberak ( 2016-08-01 05:40:21 -0500 )edit
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Asked: 2015-03-27 13:14:04 -0500

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Last updated: Oct 07 '16