Sajhauser, looking back what I did, and what you told I was wrong; I think, the conditions are well met. It had worked for the program and it gave right output for ever date I checked. However, I ended up using this code: if (y % 4 ==0 && y % 100 != 0 || y%100 == 0 && y % 400 == 0) return true; else return false; Not that I can change my codes back, but let me know if you still think it is incorrect: