Lesson 2 of 20Getting Started15 min

Variables and Data Types

A variable is a named location used to store a value. C++ is strongly typed, so the variable’s data type determines what kind of value it can hold.

Common Data Types

Type	Example	Use
`int`	`25`	Whole numbers
`double`	`88.5`	Decimal numbers
`char`	`'A'`	One character
`bool`	`true`	True or false values
`string`	`"Alice"`	Text

Declaring and Initialising Variables

Variables example

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

int main()
{
    string name = "Alice";
    int age = 20;
    double score = 88.5;
    char grade = 'A';
    bool enrolled = true;

    cout << "Name: " << name << endl;
    cout << "Age: " << age << endl;
    cout << "Score: " << score << endl;
    cout << "Grade: " << grade << endl;
    cout << boolalpha << "Enrolled: " << enrolled << endl;

    return 0;
}

Constants

Use const for a value that should not change while the program is running.

Constant example

const double TAX_RATE = 0.06;
double price = 100.0;
double tax = price * TAX_RATE;

Practice task

Create variables for a product name, price, quantity, and availability. Display all four values.

Lesson Summary

Store text, whole numbers, decimal values, characters, and Boolean values.