It returns me the same error even though I have changed the code. Eg: 'struct Keypoint' has no member named 'printkeypoint' but I had changed the 'struct' to 'class', still it insists there is 'struct Keypoint' with no member named 'printkeypoint' (and I am pretty sure there is such member in the class). I tried to open a new header file, copy and paste the code from the old one, and delete the old one, empty the recycle bin. Still, it insists there is a 'struct'. Can someone help me?