Data Types
In the C programming language, data types refer to an
extensive system used for declaring variables or functions of different types.
The type of a variable determines how much space it occupies in storage and how
the bit pattern stored is interpreted.
The types in C can be classified as follows:
|
S.N.
|
Types and Description
|
|
1
|
Basic Types:
They are arithmetic types and 1 consists of the two types: (a)
integer types and (b) floating-point types.
|
|
2
|
Enumerated types:
They are again arithmetic types and they are used to define variables
that can only be assigned certain discrete integer values throughout the
program.
|
|
3
|
The type void:
The type specifier void indicates that no value is available.
|
|
4
|
Derived types:
They include (a) Pointer types, (b) Array types, (c) Structure types,
(d) Union types and (e) Function types.
|
The array types and structure types are referred to
collectively as the aggregate types. The type of a function specifies the type
of the function's return value. We will see basic types in the following
section, whereas, other types will be covered in the upcoming chapters.
Integer Types
Following table gives you details about standard integer
types with its storage sizes and value ranges:
|
Type
|
Storage
Size
|
Volume
range
|
|
char
|
1 byte
|
-128 to
127 or 0 to 255
|
|
Unsigned
Char
|
1 byte
|
0 to 255
|
|
signed
Char
|
1 byte
|
-128 to
127
|
|
int
|
2 to 4
byte
|
-32,768 to
32,767 or -2,147,483,648 to 2,147,483,647
|
|
Unsigned
int
|
2 to 4
byte
|
0 to
65,535 or 0 to 4,294,967,295
|
|
short
|
2 byte
|
-32,768 to
32,767
|
|
Unsigned
short
|
2 byte
|
0 to
65,535
|
|
long
|
4 byte
|
-2,147,483,648
to 2,147,484,647
|
|
Unsigned
long
|
4 byte
|
0 to 4,294,967,295
|
To get the exact size of a type or a variable on a
particular platform, you can use the sizeof
operator. The expressions sizeof(type)
yields the storage size of the object or type in bytes.
Floating-Point Types
Following table gives you details about standard
floating-point types with storage sizes and value ranges and their precision:
|
Type
|
Storage Size
|
Value range
|
Precision
|
|
float
|
4 byte
|
1.2E-38 to 3.4E+38
|
6 decimal places
|
|
double
|
8 byte
|
2.3E-308 to 1.7E+308
|
15 decimal places
|
|
long double
|
10 byte
|
3.4E-4932 to 1.1E+4932
|
19 decimal places
|
The header file float.h
defines macros that allow you to use these values and other details about the
binary representation of real numbers in your programs.
The void Type
The void type specifies that no value is available. It is
used in three kinds of situations:
|
S.N.
|
Types and
Description
|
|
1
|
Function
returns as void
There are various functions in C which do
not return value or you can say they return void. A function with no return
value has the return type as void. For example, void exit (int status);
|
|
2
|
Function
arguments as void
There are various functions in
C which do not accept any parameter. A function with no parameter can accept
as a void. For example, int
rand(void);
|
|
|
Pointers
to void
A pointer of type void *
represents the address of an object, but not its type. For example a memory
allocation function void
*malloc( size.t size); returns a pointer to void which can be
casted to any data type.
|
The void type may not be understood to you at this point, so
let us proceed and we will cover these concepts in the upcoming chapters.
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