Data type and Modifiers in C++

A data type specifies the type of data a variable can store, for example, integer, floating point, character, etc. C++ supports the following data types:

• Primary or Built-in or Fundamental data type
• Derived data types
• User-defined data types

Primary or Built-in or Fundamental data type:

These data types are built-in or predefined data types that the user can use to declare variables directly. These are:

Integer	Boolean
Character	Double Floating Point
Floating Point	Wide Character
Valueless or Void

Derived data types:

Derived Data Types are data types that are derived from primitive or built-in data types. These can be classified into four types:

Function	Array
Reference	Pointer

User-defined data types:

These data types are specified by the user. The following user-defined datatypes are available in C++:

Class	Structure
Union	Typedef defined Datatype
Enumeration

 Memory Size and Range of Primitive Data Types:

Let’s take a look at fundamental data types. Its size is based on a 32-bit operating system.

Data Types	Memory Size	Range
char	1 byte	-128 to 127
signed char	1 byte	-128 to 127
unsigned char	1 byte	0 to 127
short	2 byte	-32,768 to 32,767
signed short	2 byte	-32,768 to 32,767
unsigned short	2 byte	0 to 32,767
int	2 byte	-32,768 to 32,767
signed int	2 byte	-32,768 to 32,767
unsigned int	2 byte	0 to 32,767
short int	2 byte	-32,768 to 32,767
signed short int	2 byte	-32,768 to 32,767
unsigned short int	2 byte	0 to 32,767
long int	4 byte
signed long int	4 byte
unsigned long int	4 byte
float	4 byte
double	8 byte
long double	10 byte

Enum Datatype in C++:

An enumerated type specifies an optional type name as well as a set of zero or more identifiers that can be used as type values. Each enumerator is a constant of the enumeration’s type.

The keyword enum must be used when creating an enumeration. An enumeration type’s general form is

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

For instance,

enum day(monday, tuesday, wednesday, thursday, friday) d;

Modifiers in C++:

In C++, modifiers are used to change or add meaning to database types. It is used as a prefix to change the meaning of primitive data types. A modifier is used to alter the meaning of a basic type so that it better meets the needs of different situations. Following are the four datatype modifiers in C++,

• signed
• unsigned
• long
• short

Important Points to remember:

• To integer base types, the modifiers signed, unsigned, long, and short can be applied.
• Furthermore, for char, signed and unsigned can be used, and for double, long can be used.
• Signed and unsigned modifiers can also be used as prefixes to long or short modifiers. Unsigned long int, for example.
• Unsigned, short, and long integers can be declared using a shorthand notation in C++.
• Without int, you can simply use the words unsigned, short, or long. It implies int automatically.
• Size hierarchy : short int < int < long int
• The size hierarchy for floating point numbers is: float < double < long double

Note: also read about the OOPs Concepts in C++

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