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During
programming we need to store data. This data is stored in variables. Variables
are locations in memory for storing data. The memory is divided into blocks. It
can be viewed as pigeon-holes. You can also think of it as PO Boxes. In post
offices there are different boxes and each has an address. Similarly in memory,
there is a numerical address for each location of memory (block). It is
difficult for us to handle these numerical addresses in our programs. So we
give a name to these locations. These names are variables. We call them
variables because they can contain different values at different times.
The variable
names in C may be started with a character or an underscore ( _ ). But avoid
starting a name with underscore ( _ ). C has many libraries which contain
variables and function names normally starting with underscore ( _ ). So your
variable name starting with underscore ( _ ) may conflict with these variables
or function names.
In a program
every variable has
o Name o
Type o Size o Value
The
variables having a name, type and size (type and size will be discussed later)
are just empty boxes. They are useless until we put some value in them. To put
some value in these boxes is known as assigning values to variables. In C
language, we use assignment operator for this purpose.