C++ Data Types

Data types in any of the language means that what are the various type of data the variables can have in that particular language. Information is stored in a computer memory with different data types. Whenever a variable is declared it becomes necessary to define data type that what will be the type of data that variable can hold.

Data Types available in C++:

1. Primary(Built-in) Data Types:
   • character
   • integer
   • floating point
   • boolean
   • double floating point
   • void
   • wide character
2. User Defined Data Types:
   • Structure
   • Union
   • Class
   • Enumeration
3. Derived Data Types:
   • Array
   • Function
   • Pointer
   • Reference

Both C and C++ compilers support the fundamental i.e. the built-in data types. Taking void as exception, the basic data types may have several modifiers, and these modifiers are used to serve the data types in various situations.

The lists of modifiers used in C++ are:

• signed
• unsigned
• long
• short

Character Data Types

Data Type (Keywords)	Description	Size	Typical Range
char	Any single character. It may include a letter, a digit, a punctuation mark, or a space.	1 byte	-128 to 127 or 0 to 255
signed char	Signed character.	1 byte	-128 to 127
unsigned char	Unsigned character.	1 byte	0 to 255
wchar_t	Wide character.	2 or 4 bytes	1 wide character

Integer Data Types

Data Type (Keywords)	Description	Size	Typical Range
int	Integer.	4 bytes	-2147483648 to 2147483647
signed int	Signed integer. Values may be negative, positive, or zero.	4 bytes	-2147483648 to 2147483647
unsigned int	Unsigned integer. Values are always positive or zero. Never negative.	4 bytes	0 to 4294967295
short	Short integer.	2 bytes	-32768 to 32767
signed short	Signed short integer. Values may be negative, positive, or zero.	2 bytes	-32768 to 32767
unsigned short	Unsigned short integer. Values are always positive or zero. Never negative.	2 bytes	0 to 65535
long	Long integer.	4 bytes	-2147483648 to 2147483647
signed long	Signed long integer. Values may be negative, positive, or zero.	4 bytes	-2147483648 to 2147483647
unsigned long	Unsigned long integer. Values are always positive or zero. Never negative.	4 bytes	0 to 4294967295

Floating-point Data Types

Data Type (Keywords)	Description	Size	Typical Range
float	Floating point number. There is no fixed number of digits before or after the decimal point.	4 bytes	+/- 3.4e +/- 38 (~7 digits)
double	Double precision floating point number. More accurate compared to float.	8 bytes	+/- 1.7e +/- 308 (~15 digits)
long double	Long double precision floating point number.	8 bytes	+/- 1.7e +/- 308 (~15 digits)

Boolean Data Type

Data Type (Keywords)	Description	Size	Typical Range
bool	Boolean value. It can only take one of two values: true or false.	1 byte	true or false

Variables sizes might be different in your PC from those shown in the above table, depending on the compiler you are using.

Below example will produce correct size of various data type, on your computer.

Example:

#include <iostream>
using namespace std;

int main() {
 cout << "Size of char is " << sizeof(char) << endl;
 cout << "Size of int is " << sizeof(int) << endl;
 cout << "Size of float is " << sizeof(float) << endl;
 cout << "Size of short int is " << sizeof(short int) << endl;
 cout << "Size of long int is " << sizeof(long int) << endl;
 cout << "Size of double is " << sizeof(double) << endl;
 cout << "Size of wchar_t is " << sizeof(wchar_t) << endl;
 return 0;
}

Program Output:

Size of char is 1

Size of int is 4

Size of float is 4

Size of short int is 2

Size of long int is 4

Size of double is 8

Size of wchar_t is 4

Enum Data Type

This is an user defined data type having finite set of enumeration constants. The keyword ‘enum‘ is used to create enumerated data type.

Syntax:

enum enum-name {list of names}var-list;

enum mca(software, internet, seo);

Typedef

It is used to create new data type. But it is commonly used to change existing data type with another name.

Syntax:

typedef [data_type] synonym;

or

typedef [data_type] new_data_type;

Example:

typedef int integer;
integer rollno;