Data Types in C language

Data Types

The nature of variable is referred as data type.The data type determines the kind of data which is going to be stored in the variable declared of that type.  It plays important role to declare variables. It prevents invalid data entry in the program. The biggest advantage of data type is efficient use of memory space.

Data type can be classified into following sub-heads.

1.Basic Data Types

2.User Defined Data Types

3.Derived Data Types

1.Basic data types :

Data Type	Descriptions	Keyword	Memory	Conversion  String	Range (on 16 bit machine)
Integer	Whole number	int	2 bytes	%d	-32768 to +32767
Character	Single characte	char	1 bytes	%c	-128 to +127
Floating Point	Real number (precision:- 06 places)	float	4 bytes	%f	3.4e-38 to + 3.4e+38
Double-Precision floating point	Real number (precision:- 12 places)	double	8 bytes	%lf	1.7e-308 to 1.7e+308

2.User defined Data Types:

         User defined data types are those data types that define by the users.

 a.Type Defination:-

                                   Type definition is used to provide an alternate name to existing data type.

Type definition does not create a new data type; it just assign a new name.

The keyword “typedef”  is used to fulfil the purpose  means using keyword “typedef” user can change name of data type.

 Ex- if user want change name of data type ‘int’ to ‘number’ than use the “typedef” keyword.

The Syntax is:

     typedef  ‘data type’  ‘new name’ ;

ex-

   #include<stdio.h>

   typedef int number

   void main()

  {

     number   x=1;

      printf(“X=%d”,x);

  }

  output:- 1

b.Enumerator:  

Enumerator data type is defined to store specific set of constant.

Enumerator data type essentially defines a set of constants of the type int.

The variables of enumerated data type can store only one value from

Specific set only. The Keyword “enum” is used to create  enumerated data type

The syntax is

         enum “enum_tag” {enumeration constants};

         enum enum_tag  variables;

   Enumerated data type makes programs more readable(advantage).

The enumerated values cannot be used directly in I/O functions(Disadvantages)

# include<stdio.h>

enum division  {Fail,First,Second,Third} ;   /* 'enum division' is a user defined data type */

void main()

{

  enum division status;            /*'status' is a variable of data type 'enum division' */

  status=First;                        /* value of 'status' is first*/

if(status==First)

  printf("Congratulation");

else

     printf("Put Efforts");

}

3. Derived Data Type:

Derived data types are devised from existing data types. “C” language supports various derived data type like array, structure, union, pointer etc.

Array is the collection of homogeneous data while structure and union are the collection of heterogeneous data .pointer stores the address of some other variables.  

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