C++ Variables - C++ Tutorial

Variables act as containers that store data in a program. They allow you to save, modify, and manipulate information while writing efficient code.

Different Types of Variables

C++ provides several data types, each designed for storing specific types of values:

int → Stores whole numbers without decimals (e.g., 120, -45)
double → Holds floating-point numbers (e.g., 25.75, -8.99)
char → Stores single characters (e.g., 'M', 'B') within single quotes
string → Holds text (e.g., "Harley Davidson", "Ducati") within double quotes
bool → Holds true/false values, useful for logical decisions

Declaring and Assigning Variables

To define a variable, specify its type and give it a value:

Syntax:

type variableName = value;

C++
​x
 
type variableName = value;​

type → Defines what kind of data the variable holds (int, double, etc.)
variableName → The name assigned to the variable
= → Used to assign a value to the variable

Storing a Number

#include <iostream>
using namespace std;

int main() {
    int engineCC = 1000; // Engine capacity in cc
    cout << "Engine capacity: " << engineCC << " cc";

    return 0;
}

C++
 
#include <iostream>using namespace std;​int main() {    int engineCC = 1000; // Engine capacity in cc    cout << "Engine capacity: " << engineCC << " cc";​    return 0;}

Declaring a Variable Without Assigning a Value

#include <iostream>
using namespace std;

int main() {
    int engineCC;  // Declaring the variable
    engineCC = 1000;  // Assigning the value

    cout << "Engine capacity: " << engineCC << " cc";

    return 0;
}

C++
 
#include <iostream>using namespace std;​int main() {    int engineCC;  // Declaring the variable    engineCC = 1000;  // Assigning the value​    cout << "Engine capacity: " << engineCC << " cc";​    return 0;}

Modifying a Variable

Once assigned, a variable can change its value during execution.

Example: Updating a Variable

#include <iostream>
using namespace std;

int main() {
    int engineCC = 1000;  // Initial value
    engineCC = 650;       // Updated value

    cout << "Updated engine capacity: " << engineCC << " cc";

    return 0;
}

C++
 
#include <iostream>using namespace std;​int main() {    int engineCC = 1000;  // Initial value    engineCC = 650;       // Updated value​    cout << "Updated engine capacity: " << engineCC << " cc";​    return 0;}

Other Variable Types

C++ offers multiple data types to handle different kinds of values:

#include <iostream>
using namespace std;

int main() {
    int speed = 220;           // Whole number (integer)
    double mileage = 15.75;    // Decimal number (floating point)
    char grade = 'A';          // Single character
    string brand = "Kawasaki"; // Text (string)
    bool isAvailable = true;   // Boolean (true/false)

    cout << "Speed: " << speed << " km/h" << endl;
    cout << "Mileage: " << mileage << " km/L" << endl;
    cout << "Grade: " << grade << endl;
    cout << "Brand: " << brand << endl;
    cout << "Availability: " << isAvailable << endl;

    return 0;
}

C++
 
#include <iostream>using namespace std;​int main() {    int speed = 220;           // Whole number (integer)    double mileage = 15.75;    // Decimal number (floating point)    char grade = 'A';          // Single character    string brand = "Kawasaki"; // Text (string)    bool isAvailable = true;   // Boolean (true/false)​    cout << "Speed: " << speed << " km/h" << endl;    cout << "Mileage: " << mileage << " km/L" << endl;    cout << "Grade: " << grade << endl;    cout << "Brand: " << brand << endl;    cout << "Availability: " << isAvailable << endl;​    return 0;}

Displaying Variables in Output

To print a variable along with text, use the cout object with the << operator:

#include <iostream>
using namespace std;

int main() {
    int topSpeed = 180;  // Declaring and initializing the variable

    cout << "The motorcycle's top speed is " << topSpeed << " km/h.";

    return 0;
}

C++
 
#include <iostream>using namespace std;​int main() {    int topSpeed = 180;  // Declaring and initializing the variable​    cout << "The motorcycle's top speed is " << topSpeed << " km/h.";​    return 0;}

Adding Variables Together

You can perform calculations using multiple variables.

Example: Addition

#include <iostream>
using namespace std;

int main() {
    int speed1 = 120;
    int speed2 = 150;
    int totalSpeed = speed1 + speed2;

    cout << "Total combined speed: " << totalSpeed << " km/h";

    return 0;
}

C++
 
#include <iostream>using namespace std;​int main() {    int speed1 = 120;    int speed2 = 150;    int totalSpeed = speed1 + speed2;​    cout << "Total combined speed: " << totalSpeed << " km/h";​    return 0;}

Output: 270