Variables, Keywords and Datatypes.

keyword:

Keywords are those words whose meaning has already been explained to the C compiler. A keyword is a reserved word for C. This cannot be used as an identifier by the user in his program. The set of C keywords is here:

Variables:

A variable is not a fundamental aspect of a computer language. It is a location in the computer memory which can store data and is given by a symbolic name for every reference.

Constant:

A constant is an entity that cant be changed. It is a memory fixed for some variable for certain value.

For Example: int, float

Data types:

Data types in C refer to an extensive system used for declaring variable or functions of different types. The types of variables determine how much space it occupies in storing and how the bit pattern is interpreted.

Four types of Data types:

1. Basic Types:

        Integer data type.

        Float data type.

2.Enum Types:

They are arithmetic types and they are used to define variables that can only assign certain discrete integer values throughout the program.

3. Void Types:

This type of specifier indicates that no value is available.

4. Derived Types:

        Pointers

        Array

        union

        Function

        Structure

Range of Data Types: