Variables in C

A variable is a named data storage location in your computer's memory. By using a variable in the program, we are just referring to the data in our memory. To use the variables in our program, we must know how to create them. In creating a variable, there are certain conditions to be followed. They are

Conditions to setting Variable Names:

• The name can contain letters, digits and the underscore character i.e., '_'.
• The first character of the name must be a letter or an underscore.
• If there is any change in the case of the letters, then they are treated as two different variables i.e., count  and Count are two different variables.
• Keywords can't be a variable.

Examples of variable names:

1. percent --> Correct
2. double  --> Incorrect because double is a keyword.
3. 9cloud  --> Incorrect as the variable name can't start with number.
4. abc#xy --> Incorrect because of using special character #.
5. _hello   --> Correct
6. Hello_  --> Correct
7. abc1     --> Correct

To know about the Keywords or the Reserved words, refer here.

For most of the C compilers, a variable name can be up to 31 characters long. Actually it can be longer than 31 characters but the compiler takes only first 31 characters.

Generally for a variable name with multiple words, there are two styles of using it.

• using and underscore to separate words i.e., interest_rate.
• camel notation, which means using a capital letter in the starting of the word i.e., InterestRate.