How to: Use Operator Overloading to Create a Complex Number Class (C# Programming Guide)

This example shows how you can use operator overloading to create a complex number class Complex that defines complex addition. The program displays the imaginary and the real parts of the numbers and the addition result using an override of the ToString method.


public struct Complex
    public int real;
    public int imaginary;

    // Constructor.
    public Complex(int real, int imaginary)  
        this.real = real;
        this.imaginary = imaginary;

    // Specify which operator to overload (+), 
    // the types that can be added (two Complex objects),
    // and the return type (Complex).
    public static Complex operator +(Complex c1, Complex c2)
        return new Complex(c1.real + c2.real, c1.imaginary + c2.imaginary);

    // Override the ToString() method to display a complex number 
    // in the traditional format:
    public override string ToString()
        return (System.String.Format("{0} + {1}i", real, imaginary));

class TestComplex
    static void Main()
        Complex num1 = new Complex(2, 3);
        Complex num2 = new Complex(3, 4);

        // Add two Complex objects by using the overloaded + operator.
        Complex sum = num1 + num2;

        // Print the numbers and the sum by using the overridden 
        // ToString method.
        System.Console.WriteLine("First complex number:  {0}", num1);
        System.Console.WriteLine("Second complex number: {0}", num2);
        System.Console.WriteLine("The sum of the two numbers: {0}", sum);

        // Keep the console window open in debug mode.
        System.Console.WriteLine("Press any key to exit.");
/* Output:
    First complex number:  2 + 3i
    Second complex number: 3 + 4i
    The sum of the two numbers: 5 + 7i

See Also

C# Programming Guide
C# Operators
operator (C# Reference)
Why are overloaded operators always static in C#?