How is the oath or affirmation taken by the President before he enters into office?
The oath or affirmation taken by the President before he enters into office is as follows:

"I, A.B., do swear in the name of God that I will faithfully execute the office of President (or discharge the functions of the President) of India and will to the best of my ability preserve, protect and defend the Constitution and the law and that I will devote myself to the service and well-being of the people of India."