C++ Data Types

Basic Data Types

C++ comes with several built-in, or primitive, data types. The ones you will use most often are int for whole numbers, double for decimals, char for single characters, bool for true/false values, and string for text (which comes from the standard library).

#include <iostream>
#include <string>
using namespace std;

int main() {
  int quantity = 3;
  double price = 4.50;
  char grade = 'B';
  bool inStock = true;
  string item = "Notebook";

  cout << item << " x" << quantity << endl;
  cout << "Price each: " << price << endl;
  cout << "Grade: " << grade << endl;
  cout << "In stock: " << inStock;
  return 0;
}

Checking a Type's Size

Each type takes up a certain amount of memory, measured in bytes. The sizeof operator lets you see how big a type is on your system. Sizes can vary between machines, but the relative order is stable.

#include <iostream>
using namespace std;

int main() {
  cout << "int: " << sizeof(int) << " bytes" << endl;
  cout << "double: " << sizeof(double) << " bytes" << endl;
  cout << "char: " << sizeof(char) << " byte";
  return 0;
}

• Use int when you only need whole numbers.
• Use double when you need fractional values.
• Use char for a single letter or symbol.
• Use bool for yes/no or on/off style values.