Use of stdin and stdout

Question

What is the basic concept of stdin and stdout in c and how am i supposed to use it ?

Answer 1

STDIN and STDOUT are the file pointers that are automatically defined at the moment of the program execution:

stdin gets input from the keyboard, functions that read stdin are:
- scanf()
- gets()
- getchar()

stdout sends data to the screen, functions that write to stdout are:
- printf()
- puts()
- putchar()