C++ Data Types

Data types in any programming language mean that what are the various types of data variables can have in that particular language. C++ data types define the type of data that variables can hold.

Information is stored in computer memory along with different data types. Whenever a variable is declared, it becomes necessary to define a data type that will be the type of data that the 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 an exception, the basic data types may have several modifiers that 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 differ in your PC from those shown in the above table, depending on the compiler you are using.

The below example will produce the correct size of various data types 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 a user-defined data type having a finite set of enumeration constants. The keyword 'enum' is used to create an enumerated data type.

Syntax:

enum enum-name {list of names}var-list;
enum mca(software, internet, seo);

Typedef

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

Syntax:

typedef [data_type] synonym;

or

typedef [data_type] new_data_type;

Example:

typedef int integer;
integer rollno;
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