Create class Complex number in C#

Question

I tried to create class Complex number in C# with two different constructor, the first constructor takes real part and imaginary part, the second constructor takes module and argument.

public class Complex
{
    public Complex() { }

    private Complex(double _re, double _im)
    {
        re = _re;
        im = _im;
    }

    public static double Complex_FromCartesian(double _re, double _im)
    {
        return new Complex(_re, _im);
    }

    public static double Complex_FromPolar(double _mod, double _arg)
    {
        var _re = _mod * Math.Cos(_arg);
        var _im = _mod * Math.Sin(_arg);
        return new Complex(_re, _im);
    }

    public static Complex operator +(Complex num1, Complex num2)
    {
        return new Complex(num1.re + num2.re, num2.im + num2.im);
    }

    public static Complex operator -(Complex num1, Complex num2)
    {
        return new Complex(num1.re - num2.re, num2.im - num2.im);
    }

    public double Re { get; set; }
    public double Im { get; set; }

    private double re, im;
}

}

but I got the same error in both constructors
enter image description here
How to fix that?

Change the return type of these static functions to Complex? — Damien_The_Unbeliever
– Damien_The_Unbeliever, Commented Jul 4, 2013 at 8:52
the method Complex_FromCarhesion returns double in the header but you want to return a Complex (return new Complex). Change in the header to return a Complex. — VasileF
– VasileF, Commented Jul 4, 2013 at 8:53
Either return Complex or override implicit cast in Complex. — Leri
– Leri, Commented Jul 4, 2013 at 8:54
A side note: Why are you using static methods instead of real contructors? — Treb
– Treb, Commented Jul 4, 2013 at 8:57
@Treb Because those static methods would have the same signature if they were converted to constructors. TimeSpan struct is good example of this. I really don't understand why Complex is not struct here. — Leri
– Leri, Commented Jul 4, 2013 at 9:03

DGibbs · Accepted Answer · 2013-07-04 08:53:52Z

8

Your method returns a double but you're trying to return a Complex type

Change:

public static double Complex_FromCartesian(double _re, double _im)
{
    return new Complex(_re, _im);
}

To:

public static Complex Complex_FromCartesian(double _re, double _im)
{
    return new Complex(_re, _im);
}

answered Jul 4, 2013 at 8:53

DGibbs

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2 Comments

Heidel Over a year ago

But how to use this constructor?

MoonKnight Over a year ago

It's not a constructor. This is a static method that instanciates your class type. Call is like Complex c = Complex.Complex_FromCartiesian(x, y);...

MoonKnight · Accepted Answer · 2013-07-04 08:52:46Z

6

Change the return type of that method to Complex.

answered Jul 4, 2013 at 8:52

MoonKnight

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Comments

gzaxx · Accepted Answer · 2013-07-04 08:52:52Z

5

You cant return Complex when double is expected.

public static Complex Complex_FromCartesian(double _re, double _im)
{
   return new Complex(_re, _im);
}

answered Jul 4, 2013 at 8:52

gzaxx

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Comments

Faster Solutions · Accepted Answer · 2013-07-04 08:54:09Z

3

Your constructor is fine. The problem is that you've specified a return type of double and you're returning a class of type "Complex".

answered Jul 4, 2013 at 8:54

Faster Solutions

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Comments

Shafiq Abbas · Accepted Answer · 2013-07-04 09:26:28Z

2

This error occurs when the data types mismatch. It is expecting "complex" datatype and you are telling it is double. Change double to complex

answered Jul 4, 2013 at 9:26

Shafiq Abbas

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