0 Primary data types in C

Primary data types are those which are not composed of other data types. There are five primary data types:

1.Integer

2.Float

3.Character

4.Void

Integer types:

Integers are whole numbers with a range of values, range of values are machine dependent. Generally an integer occupies 2 bytes memory space and its value range limited to -32768 to +32767 (that is, -2¹⁵ to +2¹⁵-1). A signed integer use one bit for storing sign and rest 15 bits for number.

To control the range of numbers and storage space, C has three classes of integer storage namely short int, int and long int. All three data types have signed and unsigned forms. A short int requires half the amount of storage than normal integer. Unlike signed integer, unsigned integers are always positive and use all the bits for the magnitude of the number. Therefore the range of an unsigned integer will be from 0 to 65535. The long integers are used to declare a longer range of values and it occupies 4 bytes of storage space.

Syntax: int <variable name>; like

int num1;

short int num2;

long int num3;

Example: 5, 6, 100, 2500.

Floating Point Types:

The float data type is used to store fractional numbers (real numbers) with 6 digits of 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 and takes double space (8 bytes) than float. To extend the precision further we can use long double which occupies 10 bytes of memory space.

Syntax:          float <variable name>; like
float num1;
double num2;
long double num3;

Example:      9.125, 3.1254.

Character Type:

Character type variable can hold a single character. As there are singed and unsigned int (either short or long), in the same way there are signed and unsigned chars; both occupy 1 byte each, but having different ranges. Unsigned characters have values between 0 and 255, signed characters have values from –128 to 127.

Syntax: char <variable name>; like
char ch = ‘a’;

Example:      a, b, g, S, j.

Void Type:

The void type has no values therefore we cannot declare it as variable as we did in case of integer and float.
The void data type is usually used with function to specify its type. The concept of returning values will be discussed in detail when we will discuss functions.