Variables in C

Variables in C

A variable is an identifier used to represent some specified type of information . A variable represents a single data item , that is a numerical quantity or a character constant etc.

The data item must be assigned to the variable at some point in the program. The data items can be accessed later in the program by simply referring to variable name.

The information represented by the variable can change during the execution of the program by assigning different data items at various places with in the program.

But the data type associated with the variable cannot change.

Variable Declaration :

Before a variable is used in c program it must be declared.

The syntax for variable declaration is a shown below:

        Datatype (space) Varaiablename;

Example:

        int  a ;

here, int is the data typeof the variable

        there should be a space between the datatype and variablename

        a is the variable name

        each statement in c should be terminated by ;(semicolon)

That means the ‘a’ is a variable and it can store only integer values.

We can also declare multiple variables of similar datatypes as follows:

        Datatype   variablename_1,variablename_2,..,variablename_n;

Example:

        float  a,b,c,d,e;

here all the variables a,b,c,d,e belongs to float type.

        Char  name[20];

Here name is a character string which can store up to 19 characters followed by a null character.

Initial values can be assigned to the variables at the type declaration itself.

The syntax for it is as follows:

        Datatype  variablename = value;

Example:

        Char  star = ‘b’;

        int  num =4;

that means star now holds the value b and num holds the value 4.

“ =  “ (equal to) is called as assignment operator because it assigns the value from right to left.

Statements:

A statement causes the computer to carry some action.

There are two types of statements in c. They are

·       simple

·       compound

A simple statement consist of expression followed by semi colen.

Example :

                main()

{

                        int  a,b;

                        a=5;

                        b=a+6;

                }

The above statements says that…

Line 1: a and b are integer variables ,

Line 2: the store the value of a is 5,

Line 3: add the value at variable a with 6 , the value of a is 5, so 5+6 is     11 .

Example of compound statement,

{

                int pi=3.14;

                circumference = 2*pi*radius;

                area=pi*radius*radius;

        }

The compound statement provides the capability of embedding statements with in other statements.

Thank you …