Kotlin Operator Overloading

Operator Overloading allows us to overload operators for our Custom Classes.
Let us say we have a Complex class to represent Complex numbers.
And we want to add two Complex numbers.
Or lets say we want to subtract two Complex numbers.
We would rather use + operator or - operator to add or subtract complex numbers.

Example:

var C1 = Complex(1, 3)
var C2 = Complex(2,4)
var C3 = C1 + C2
var C4 = C2 - C1

Let us see how we can create a Complex class and then overload plus and minus operator to achieve our goal.

class Complex(val real: Int, val imaginary: Int)
{
	operator fun plus(c: Complex): Complex
	{
	return Complex(real + c.real, imaginary + c.imaginary)
	}

	operator fun minus(c: Complex): Complex
	{
	return Complex(real - c.real, imaginary - c.imaginary)
	}
    
    override fun toString(): String
    {
        return this.real.toString() + " + " + this.imaginary.toString()  + "i"
    }
}

fun main(args: Array<String>)
{	
	var C1 = Complex(1,3)
	var C2 = Complex(2,4)
	var C3 = C1 + C2
	var C4 = C2 - C1
    println(C3)
    println(C4)
}

Output:
3 + 7i
1 + 1i