Describe the basic data types used in C language.
Data types in C language can be classified into the
following categories.
1. Primary Data type
2. User Defined Data
type
3. Derived Data type
4. Empty Data set.
Primary Data type
1) int
2) float
3) double
4) char
int: These are whole numbers, both positive and
negative. Unsigned integers (positive values only) are supported. In addition,
there are short and long integers. Its data range is -32768 to +32767
The keyword used to define integers is: int.
An example of an integer value is 32. An example of
declaring an integer variable called sum is:
int sum;
sum = 20;
float: These are numbers which contain fractional
parts, both positive and negative. The keyword used to define float variables
is: float. Its data range is -3.4e38 to +3.4e38.
An example of a float value is 34.12. An example of
declaring a float variable called money is:
float money;
money =
0.12;
double:double is used to define BIG floating point
numbers. It reserves twice the storage for the number. Its data range is -1.7e38
to +1.7e38. An example:
double Atoms;
Atoms =
2500000;
Char: These are single characters. The keyword used
to define character variables is: char
An example of a character value is the letter A. An example
of declaring a character variable called letter is:
char letter;
letter =
'A';
USER DEFINED DATA TYPE
User defined data
type are those which are derive from the basic data types. Some of the user
defined data types are
1) Type definition
2) Enumerated
Type definition: In C language a user can define an
identifier that represents an existing data type.
The user defined data type identifier can later be used to
declare variables.
Syntax is: typedef datatype identifier;
Example:
typedef int
marks;
Now marks can be
used to declare integer variables as
marks
mark1,mark2;
Enumerated: Enumerated data types are those in which
a variable can contain only some specific set of values. This is done using the
key word “enum”.
example:
enum months = {
“January”, “Feburary”, “March”, “April”, “May”, “June”, “July”, “August”,
“September”, “October”, “November”, “December” };
months m1, m2;
here the variables m1
and m2 are of enumerated data types. It can hold only the values from January
to December as declared.
Derived Data type:
1) Arrays
2) Structures
Arrays
Arrays can be defined
as the collection of similar type of data. It can also be called as subscripted
variables.
example:
int Mark[100];
here the variable
mark is defined as an array and it can hold 100 values of type integer. Each
value can be accessed as Mark[0], Mark[1], ……. Mark[99]
Structures
Structures are
nothing but a collection of data items. Unlike in arrays, it can hold set of
data items of different data types under a single name. This data type can be
created using the keyword “struct”
example:
struct student
{
int rno;
char name[25];
float avg;
};
struct student s1,
s2;
In the above example,
student is an user defined data type. The structure variable s1 consist of 3
values namely rno, name and avg.
EMPTY DATA SET:
As the name indicates, it contains nothing or a NULL value.
This data type is used to specify return values of function. If there is
nothing to return from a function, the return type can be specified as “void”
example:
void main()
{
-----
------
}
