Example: Quadratic Equation Roots using Class in C++

// Quadratic Equation Roots using Class
#include <iostream>  // For input/output operations
#include <cmath>     // For sqrt() and pow() functions
#include <iomanip>   // For setprecision()

using namespace std;

// Define a class to represent a Quadratic Equation
class QuadraticEquation {
private:
    double a, b, c; // Coefficients of the quadratic equation

public:
    // Constructor to initialize the coefficients
    QuadraticEquation(double coeffA, double coeffB, double coeffC) {
        a = coeffA;
        b = coeffB;
        c = coeffC;
    }

    // Method to calculate and display the roots
    void findRoots() {
        if (a == 0) {
            cout << "Invalid quadratic equation: 'a' cannot be zero." << endl;
            return;
        }

        double discriminant = b * b - 4 * a * c;
        double root1, root2;

        cout << fixed << setprecision(2); // Format output to 2 decimal places

        if (discriminant > 0) {
            root1 = (-b + sqrt(discriminant)) / (2 * a);
            root2 = (-b - sqrt(discriminant)) / (2 * a);
            cout << "Roots are real and distinct." << endl;
            cout << "Root 1 = " << root1 << endl;
            cout << "Root 2 = " << root2 << endl;
        } else if (discriminant == 0) {
            root1 = root2 = -b / (2 * a);
            cout << "Roots are real and same." << endl;
            cout << "Root 1 = Root 2 = " << root1 << endl;
        } else { // discriminant < 0
            double realPart = -b / (2 * a);
            double imaginaryPart = sqrt(-discriminant) / (2 * a);
            cout << "Roots are complex and distinct." << endl;
            cout << "Root 1 = " << realPart << " + " << imaginaryPart << "i" << endl;
            cout << "Root 2 = " << realPart << " - " << imaginaryPart << "i" << endl;
        }
    }
};

int main() {
    // Step 1: Declare variables for coefficients
    double coeff_a, coeff_b, coeff_c;

    // Step 2: Prompt user for input
    cout << "Enter coefficient a: ";
    cin >> coeff_a;
    cout << "Enter coefficient b: ";
    cin >> coeff_b;
    cout << "Enter coefficient c: ";
    cin >> coeff_c;

    // Step 3: Create an object of QuadraticEquation class
    QuadraticEquation eq(coeff_a, coeff_b, coeff_c);

    // Step 4: Call the findRoots method to calculate and display roots
    eq.findRoots();

    return 0;
}