Data Types in C++

Data types define the a type of data variable the a variable data can hold. For example, an integer variable can hold integer data, and a character type variable can hold character data.

In C++, data types are categorized into three types:

Primitive/Built-in data types
Derived data types
Abstract/User-defined data types

Built-in Data Types

Built-in data types can be used directly by the user to declare variables. The built-in data types available in C++ are:

Data Type	Keyword
Integer	int
Character	char
Boolean	bool
Floating Point	float
Double Floating Point	double
Valueless or Void	void
Wide Character	wchar_t

Derived Data Types

Derived Data Types are those that are created by combining primitive or built-in datatypes. Thera are four types of derived-defined data types in C++:

Function
Array
Pointer
Reference

User-defined Data Types

The User-defined or abstract data types are defined by the user themselves. The different User-defined data types are:

Class
Structure
Union
Enumeration
Typedef defined Data Type

Data Type Modifiers in C++

The four modifiers available in C++ are:

Signed
Unsigned
Short
Long

The table below summarizes the variable type, the size of memory required to hold the value in memory, and the maximum and lowest values stored in such variables. The below values may vary from one compiler to another. GCC 32 bit was considered in the following values.

Data Type	Size (in bytes)	Range
char	1	-127 to 127 or 0 to 255
unsigned char	1	0 to 255
signed char	1	-127 to 127
short int	2	-32,768 to 32,767
unsigned short int	2	0 to 65,535
signed short int	2	-32,768 to 32,767
int	4	-2,147,483,648 to 2,147,483,647
unsigned int	4	0 to 4,294,967,295
signed int	4	-2,147,483,648 to 2,147,483,647
long int	8	9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
signed long int	8	-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
unsigned long int	8	0 to 18,446,744,073,709,551,615
long long int	8	-(2^63) to (2^63)-1
unsigned long long int	8	0 to 18,446,744,073,709,551,615
float	4
double	8
long double	12
wchar_t	2 or 4	1 wide character

The below program will display the correct size of various data types:


#include<bits/stdc++.h>
using namespace std;

int main() {
  cout << "Size of following Data Types in bytes: \n";
  cout << "int : " << sizeof(int) << endl;
  cout << "unsigned int : " << sizeof(unsigned int) << endl;
  cout << "short int : " << sizeof(short int) << endl;
  cout << "long int : " << sizeof(long int) << endl;
  cout << "unsigned short int : " << sizeof(unsigned short int) << endl;
  cout << "unsigned long int : " << sizeof(unsigned long int) << endl;
  cout << "long long int : " << sizeof(long long int) << endl;
  cout << "unsigned long long int : " << sizeof(unsigned long long int) << endl;
  cout << "signed char : " << sizeof(signed char) << endl;
  cout << "unsigned char : " << sizeof(unsigned char) << endl;
  cout << "wchar_t : " << sizeof(wchar_t) << endl;
  cout << "float : " << sizeof(float) << endl;
  cout << "double : " << sizeof(double) << endl;
  return 0;
}

Output

Size of following Data Types in bytes: int : 4 unsigned int : 4 short int : 2 long int : 4 unsigned short int : 2 unsigned long int : 4 long long int : 8 unsigned long long int : 8 signed char : 1 unsigned char : 1 wchar_t : 2 float : 4 double : 8