How to get image width and height in OpenCV? [duplicate]

You can use rows and cols:

cout << "Width : " << src.cols << endl;
cout << "Height: " << src.rows << endl;

or size():

cout << "Width : " << src.size().width << endl;
cout << "Height: " << src.size().height << endl;

or size

cout << "Width : " << src.size[1] << endl;
cout << "Height: " << src.size[0] << endl;