quick guide

Reading, processing and writing of data are the three
essential functions of a computer Program.Most programs take
some data as input and display the processed data often known
as information or results.There are two methods of providing
data to the program data to the program variables.One method
is to assign values to variables through the assignment
statements such as x=5, a=0 and so on. Another method to use the
input function scanf which can read data from a terminal. For
outputting results the function printf which sends results out
to a terminal is used.'C' does not have any built-in input and
output statements as part of its syntax .All input and output
operations are carried out through function calls such as
printf and scanf.There exits several functions that have more
or less become standard for input and output operation in C.
These functions are collectively known as i/o library. Each
program that uses a standard input/output function must
contain the statement, at the beginning.

#include'stdio.h'
The file name stdio.h is an input-output reader file.
The instruction #include'stdio.h'tells the compiler to search
for a file named stdio.h and place its contents at this
point in the program. when it is compiled the contents of
the header file become part of the source code.