Revision history [back]

Please, next time post your code in text rather than a picture.

I don't know what are you trying to do with your code, but remove the 'return' from the for loops you have. In addition, the OpenCV function that draws a line has the following signature:

 void line(Mat& img, Point pt1, Point pt2, const Scalar& color, int thickness=1, int lineType=8, int shift=0)

For more details; Draw a line by using the OpenCV function

To draw a line you need the image to draw the lines, and two points (and some other parameters mentioned above)

If you state what you want to do clearly, I would help you more.