C++ Data Types

A data type is the kind of value a variable holds. Each type stores its own kind of value and takes its own amount of space.

One value of each type

Three variables hold three kinds of value. Each print line shows one value.

#include <iostream>

int main() {
  int count = 42;
  double price = 3.5;
  char grade = 'A';
  std::cout << count << "\n";
  std::cout << price << "\n";
  std::cout << grade << "\n";
  return 0;
}

Sizes with sizeof

A byte is a small unit of storage. sizeof tells how many bytes a type takes.

#include <iostream>

int main() {
  std::cout << sizeof(int) << "\n";
  std::cout << sizeof(double) << "\n";
  return 0;
}

A large whole number

A long long variable holds a large whole number. The number prints whole, with no part cut off.

#include <iostream>

int main() {
  long long distance = 1234567890123;
  std::cout << distance << "\n";
  return 0;
}

Example

#include <iostream>

int main() {
  int age = 30;
  double height = 1.8;
  char initial = 'B';
  std::cout << "int: " << age << "\n";
  std::cout << "double: " << height << "\n";
  std::cout << "char: " << initial << "\n";
  return 0;
}

Key points

The int type holds whole numbers.
The double type holds decimal numbers.
The float type holds decimal numbers and takes less space than double.
The char type holds one character.
The bool type holds true or false.
The std::string type holds text.
The long long type holds whole numbers larger than int can hold.

In this example, age holds the int value 30. height holds the double value 1.8. initial holds the char value B. Each print line pairs a type name with its value.

Note

The sizeof tool tells the size of a type.

Try it Yourself

Edit the code, then press Run.

Running is simulated

#include <iostream>

int main() {
  int age = 30;
  double height = 1.8;
  char initial = 'B';
  std::cout << "int: " << age << "\n";
  std::cout << "double: " << height << "\n";
  std::cout << "char: " << initial << "\n";
  return 0;
}

C++ data types

Type	Holds	Example
int	Whole numbers	42
double	Decimal numbers	3.5
float	Decimal numbers	1.5
char	One character	'A'
bool	True or false	true
std::string	Text	"Hello"
long long	Large whole numbers	1234567890123

Exercise

Which type holds one character?

char int double bool