Single Character Constants

A Single Character constant represent a single character which is enclosed in a pair of quotation symbols.

Example for character constants are

'5'
'x'
';'
' '

All character constants have an equivalent integer value which are called ASCII Values.

String Constants

A string constant is a set of characters enclosed in double quotation marks. The characters in a string constant sequence may be a alphabet, number, special character and blank space. Example of string constants are

"VISHAL"
"1234"
"God Bless"
"!.....?"

Backslash Character Constants [Escape Sequences]

Backslash character constants are special characters used in output functions. Although they contain two characters they represent only one character. Given below is the table of escape sequence and their meanings.

Variables

A variable is a value that can change any time. It is a memory location used to store a data value. A variable name should be carefully chosen by the programmer so that its use is reflected in a useful way in the entire program. Variable names are case sensitive. Example of variable names are

Sun
number
Salary
Emp_name
average1

Any variable declared in a program should confirm to the following

1. They must always begin with a letter, although some systems permit underscore as the first character.
2. The length of a variable must not be more than 8 characters.
3. White space is not allowed and
4. A variable should not be a Keyword
5. It should not contain any special characters.

Examples of Invalid Variable names are

123
(area)
6th
%abc

First Page: C Programming - Constants and Variables