Datatypes
:
Data type is the
description of nature of data either in numeric form or in character form. It
defines a set of values and the operations that can be performed on them. C
supports different classes of datatypes. They are :
·
Integer type are defined by the keyword int.
Ex: int a;
·
Character type are defined by the keyword char.
Ex: char name;
·
Float type are defined by the keyword float.
Ex: float average;
·
String type are defined as char str[n];
Ex: char name[5];
Void :
The
data type has no values. Void is a data type that which doesnot return any
value to the calling function.
The memory requirements for each
data type will determine the permissible range of values for that type, which
may vary from one compiler to another. The size and range of these data types
differ which are shown below :
DATA TYPE
|
SIZE (Bytes)
|
RANGE
|
char or signed char
|
1
|
-128 to 127
|
unsigned char
|
1
|
0 to 255
|
int or signed int
|
2
|
-32,768 to 32,767
|
unsigned int
|
2
|
0 to 65,535
|
short int or
signed short int
|
1
|
-128 to 127
|
unsigned short int
|
1
|
0 to 255
|
long int or
signed long int
|
4
|
-2,147,483,648 to
2,147,483,647
|
unsigned long int
|
4
|
0 to 4,294,967,295
|
float
|
4
|
3.4e-38 to 3.4e+38
|
double
|
8
|
1.7e-308 to 1.7e+308
|
long double
|
10
|
3.4e-4932 to 1.1e+4932
|
1.
User-Defined Data Type :
1.
typedef:
C supports a feature
known as “ typedef (type definition) “ that allows users to define an
identifier that would represent an existing data type which can later be used
to declare variables. It is represented as
typedef type
identifier
where type
refers to an existing data type and
identifier refers to the
new name
given to the data type.
Ex :
typedef int marks;
Here marks symbolizes int. so
that they can be later used to declare variables as
marks section1,section2;
where section1
and section2 are int data type.
1.
Enumerated :
Another
user-defined data type is “ enum “
(enumerated) data type. It is defined as
enum identifier {value1,
value2, . . . . . valuen};
where identifier is
user-defined enumerated data type which can be used to
declare variables that
can have one of the values enclosed within braces.
Ex : enum Boolean { true, false };
enum Boolean t, f;
t=true; f=false; So that the compiler
will automatically assigns integer values beginning with 0. That is the enumeration constant true is assigned 0, false
assigned 1.
Declaring the
Variables :
After defining the variable
names, they must be declared to the compiler as it reserves some memory and
also specifies what type of data the variable will hold.
A variable can be
used to store a value of any data type. Variable must be separated by comma. All declarations
must be terminated by a semicolon (;).
The syntax for declaring a
variable is :
data
type variable1,variable2, . . . . . variable n;
Ex : int total;
Two types of variable
declaration can be done. They are:
1.
Local Variables
2.
Global variables
Local Variables :
"Variables that are declared inside a function are called local variables.
"Variables that are declared inside a function are called local variables.
}
Global
Variables :
Global Variable can be accessed throughout the entire
program and may be used by any piece of code. Global variables are created by
declaring them outside of a function.
Ex: #include<stdio.h>
main()
{
int
b,c; these are local variables
}
DATA TYPE
|
KEYWORD
|
character
|
char
|
integer
|
int
|
floating point
|
float
|
double floating point
|
double
|
unsigned character
|
unsigned char
|
signed character
|
signed char
|
signed short integer
|
signed short int or short
|
signed long integer
|
signed long int
|
unsigned integer
|
unsigned int
|
unsigned short integer
|
unsigned short int
|
unsigned long integer
|
unsigned long int
|
extended double floating point
|
long double
|
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