Question

I am new in C++ and working on a project with QT. I created a header file called imageconvert.h which is as follow:

class ImageConvert
{

private:
IplImage *imgHeader;
uchar* newdata;

public:

ImageConvert();
~ImageConvert();
IplImage* QImage2IplImage(QImage *qimg);
QImage* IplImage2QImage(IplImage *iplImg);
};

also I defined those public methods in imageconvert.cpp file.

Now, I want to call QImage2IplImage and IplImage2QImage from other cpp file. So i include imageconvert.h in that CPP file and called those two functions.

it gives the the following errors:

error: 'QImage2IplImage' was not declared in this scope
error: 'IplImage2QImage' was not declared in this scope

Any help would be greatly appreciated.

Answer 1

The functions you’ve defined are member functions of the ImageConvert class. You need an instance of that class to be able to call them.

Something like:

ImageConvert ic;
ic.QImage2IplImage(your_QImage_object);

If you don’t need state to do the conversion, you should make those helper functions static. Then you can call them with:

ImageConvert::QImage2IplImage(your_QImage_object);

without first creating an instance of ImageConvert. But please note that you will not be able to use imgHeader or newData in those static functions – they are member variables, only usable within an instance of that class.

You could also remove these functions from your class and put them in a namespace.