Problem: Write a C++ program to add and subtract two complex numbers by overloading the + and – operators.

We often overload an operator in C++ to operate on user-defined objects.

If we define complex numbers as objects, we can easily use arithmetic operators such as additional (+) and subtraction (-) on complex numbers with operator overloading.

In the following C++ program, I have overloaded the + and operator to use it with the Complex class objects.

#include <iostream>
using namespace std;
 
class Complex{
public:
  float real;
  float img;

  Complex(){
    this->real = 0.0;
    this->img = 0.0;
  }

  Complex(float real, float img){
    this->real = real;
    this->img = img;
  }

  //overloading + operator
  Complex operator+(const Complex &obj){
    Complex temp;
    temp.img = this->img + obj.img;
    temp.real = this->real + obj.real;
    return temp;
  }

  //overloading - operator
  Complex operator-(const Complex &obj){
    Complex temp;
    temp.img = this->img - obj.img;
    temp.real = this->real - obj.real;
    return temp;
  }

  void display(){
    cout << this->real << " + " << this->img << "i" << endl;
  }
};
 
int main()
{
  Complex a, b, c;

  cout << "Enter real and complex coefficient of the first complex number: " << endl;
  cin >> a.real;
  cin >> a.img;

  cout << "Enter real and complex coefficient of the second complex number: " << endl;
  cin >> b.real;
  cin >> b.img;

  cout << "Addition Result: ";
  c = a+b;
  c.display();

  cout << "Subtraction Result: ";
  c = a-b;
  c.display();

  return 0;
}

Output:

Enter real and complex coefficient of the first complex number:
5 6
Enter real and complex coefficient of the second complex number:
1 2
Addition Result: 6 + 8i
Subtraction Result: 4 + 4i


Explanation:

In the above program, we have created Complex class with two attributes:

  • real: To store the real coefficient value.
  • img: To store the imaginary coefficient value.

Inside the class declaration, we have overloaded the + operator by adding the real and imaginary values of the current instance (i.e this) and the passed instance (i.e. obj), inside the operator+ method.

We store the result into a new complex object (i.e. temp) and return the same.

We do the same to overload the – operator, but instead of adding we subtract the corresponding coefficient.

In this programming example, we learned to add and subtract complex numbers using the concept of operator overloading in C++.

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