Assigning a value to an instance of a class in C# implicitly

May 31, 2022

I have a custom class, ComplexNumber, which is as you may expect a way to represent complex numbers:

class ComplexNumber
{
    double realPart;
    double imaginaryPart;

    public ComplexNumber(double real, double imaginary)
    {
        realPart = real;
        imaginaryPart = imaginary;
    }
}

The context of this question is that if you want to set default C# classes such as a double or a float to a certain value which is an integer, you can write

float f = 2;

I want to be able to write something similar like

ComplexNumber c = 2;

which will create a new variable of the ComplexNumber class with its realPart set to 2 and its imaginaryPart set to 0. To write ComplexNumber c = new ComplexNumber(2, 0) is much more tedious, and I am wondering if there is a way to create these instances of a custom class more implicitly like how the default C# classes behave.

>Solution :

You can add an implicit (or expicit) operator to your class like so:

public static implicit operator ComplexNumber(int i) => new ComplexNumber(i, 0);

That will allow you do what you want.

As you used 2 as a literal, that will be an int in C#, this then relies on the fact that int is implicitly convertable to double in the contructor call to ComplexNumber.