Variables and Data Types

Core idea

Variables store data, and data types tell C++ what kind of value each variable can hold. This is the first step toward writing programs that actually work with information.

Common beginner types

• int for whole numbers
• double for decimal numbers
• char for a single character
• bool for true or false
• std::string for text

#include <iostream>
#include <string>

int main() {
  int age = 20;
  double price = 19.99;
  char grade = 'A';
  bool isReady = true;
  std::string name = "Prathmesh";

  std::cout << name << " is " << age << " years old.\n";
}

Revision points

• A variable has a type, a name, and usually a starting value.
• Choose names that explain the value clearly.
• Use std::string when working with words or sentences.
• Start with simple values before combining them inside larger programs.

What to remember

Pick the simplest type that matches the data you are working with.

Next step

After variables make sense, control flow shows you how programs make decisions.