stdarg

stdarg

Question

• How does va_arg (and so on) implemented?
• What will happen if you call printf("%d", char)?

Answer

• Question 1:
• It is not implemented as a user program(not even in libc). It acts as if the C keyword sizeof. At compiling time, this word will be parsed by the compiler and do something to implement its funciton.
• Question 2:
• printf uses va_arg to get all the arguments. If you write %d, then it will assume that the argument is an integer(of type int). This may result in error because content is referenced by pointers.