The input and output of a function can be expressed as an ordered pair, ordered so that the first element is the input (or tuple of inputs, if the function takes more than one input), and the second is the output. In the example above, f(x) = x2, we have the ordered pair (-3, 9). If both input and output are real numbers, this ordered pair can be viewed as the Cartesian coordinates of a point on the graph of the function.

1). Formated Input Output Functions :- These function are used to Input data from a standard Input unit such as Keyboard and to get the result on standard output unit such as Monitor. As name suggest , these function follow a basic fix format. There are two Input Output functions. 1. printf() 2.