C Language :Data Type

A programming language is proposed to help programmer to process certain kinds of data and to provide useful output. The task of data processing is accomplished by executing series of commands called program. A program usually contains different types of data value and hence one must specify the type. A variable is nothing but a name of memory location where we store or keep the data, but prior to this compiler expects declaration of specific form of value to be stored in memory location and for that a concept of data types is used. C language supports pre-declaration strategy i.e. one must specify the (form) type of variable before its' use. The declaration of variable with certain data type actually specifies the value contained in variable. C has different data types for different types of data and can be broadly classified as :

• Primary data types.
• Secondary data types
  Primary data types consist following data types.

Data Types in C

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 +32768 (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 ; like int num1; short int num2; long int num3;
Example: 5, 6, 100, 2500.

Integer Data Type Memory Allocation

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 ; like float num1; double num2; long double num3;
Example: 9.125, 3.1254.

Floating Point Data Type Memory Allocation

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 ; 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. Like in our first C program we declared “main()” as void type because it does not return any value.

Regards:
Ajit R Pandey,