Input refers to accepting data while output refers to presenting data. Every program performs three main functions accepting data from user, processing it and producing the output.
In C language there are several input and output functions.
These functions are collectively found in IO.h and such IO function together form a library name stdio.h .
User will require all such library function.
These library functions are classified into three broad categories:
1. Console I/O functions
2. Disc I/O functions
3. Port I/O functions