[Solved]Error in building Qt5.4 with MS Visual Studio 2010



  • Hi, I am trying to use Qt in MS Visual Studio. I made a simple App using a pushButton to open a picture. But when I run the program, it prompts:
    error LNK2019: unresolved external symbol "private: void __thiscall myQtOpenCV::Open(void)"
    Open(void) is the slot function connected to the pushButton. It seems Open function is not working.
    I am not very good at programing, so I hope someone can help me to solve this problem.


  • Lifetime Qt Champion

    Hi and welcome to devnet,

    Might be a silly question but did you implement that slot ? Even if it does nothing you need it.



  • Thanks for your reply.
    I implemented it simply with OpenCV functions in the .cpp file:
    @void Open()
    {
    cv::Mat image = cv::imread("image.jpg");
    cv::namedWindow("Original Image");
    cv::imshow("Original Image", image);
    }
    @
    I can’t see where I went wrong. Here is the code in the .h file.
    @#ifndef MYQTOPENCV_H
    #define MYQTOPENCV_H

    #include <QtWidgets/QMainWindow>
    #include <QFileDialog>
    #include "ui_myqtopencv.h"
    #include "opencv2/opencv.hpp"

    class myQtOpenCV : public QMainWindow
    {
    Q_OBJECT

    public:
    myQtOpenCV(QWidget *parent = 0);
    ~myQtOpenCV();

    private:
    Ui::myQtOpenCVClass ui;

    private slots:
    void Open();
    };

    #endif // MYQTOPENCV_H
    @



  • I have solved this problem. Just my silly mistake. The function should be implemented like this @void myQtOpenCV::Open(){}@


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