C Programming Language - Data Types

In this tutorial you will learn about C language data types, Primary data type, Integer Type, Floating Point Types, Void Type, Character Type, Size and Range of Data Types on 16 bit machine, derived data type, Declaration of Variables, User defined type declaration, Declaration of Storage Class, auto, static, extern, register, Defining Symbolic Constants, Declaring Variable as Constant and Volatile Variable

A C language programmer has to tell the system before-hand, the type of numbers or characters he is using in his program. These are data types. There are many data types in C language. A C programmer has to use appropriate data type as per his requirement.

C language data types can be broadly classified as
Primary data type
Derived data type
User-defined data type

Primary data type

All C Compilers accept the following fundamental data types

1.	Integer	int
2.	Character	char
3.	Floating Point	float
4.	Double precision floating point	double
5.	Void	void

The size and range of each data type is given in the table below

DATA TYPE	RANGE OF VALUES
char	-128 to 127
Int	-32768 to +32767
float	3.4 e-38 to 3.4 e+38
double	1.7 e-308 to 1.7 e+308

Integer Type :

Integers are whole numbers with a machine dependent range of values. A good programming language as to support the programmer by giving a control on a range of numbers and storage space. C has 3 classes of integer storage namely short int, int and long int. All of these data types have signed and unsigned forms. A short int requires half the space than normal integer values. Unsigned numbers are always positive and consume all the bits for the magnitude of the number. The long and unsigned integers are used to declare a longer range of values.

Floating Point Types :

Floating point number represents a real number with 6 digits precision. Floating point numbers are denoted by the keyword float. When the accuracy of the floating point number is insufficient, we can use the double to define the number. The double is same as float but with longer precision. To extend the precision further we can use long double which consumes 80 bits of memory space.

Void Type :

Using void data type, we can specify the type of a function. It is a good practice to avoid functions that does not return any values to the calling function.

Character Type :

A single character can be defined as a defined as a character type of data. Characters are usually stored in 8 bits of internal storage. The qualifier signed or unsigned can be explicitly applied to char. While unsigned characters have values between 0 and 255, signed characters have values from –128 to 127.

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