From where will the getchar() function take input from and how does it know from where to take input....?

Answer 1

It doesn't take any parameter so the next character is it's input.
Check this https://www.tutorialspoint.com/c_standard_library/c_function_getchar.htm

Answer 2

How can a user give input....? Not programmer

Answer 3

Pls someone explain how does this getchar() work i am not understanding