One of the essential operations performed in a C language programs is to provide input values to the program and output the data produced by the program to a standard output device.
We can assign values to variable through assignment statements such as
x = 5 a = 0 ;
and so on.
Another method is to use the Input then scanf which can be used to read data from a key board.
For outputting results we have used extensively the function printf which sends results out to a terminal.
There exists several functions in ‘C’ language that can carry out input output operations.
These functions are collectively known as standard Input/Output Library.
Each program that uses standard input / out put function must contain the statement.