Question

I’d like to assign a reference to a member field. But I obviously do not understand this part of C# very well, because I failed 🙂 So, here’s my code:

public class End {
    public string parameter;

    public End(ref string parameter) {
        this.parameter = parameter;
        this.Init();
        Console.WriteLine("Inside: {0}", parameter);
    }

    public void Init() {
        this.parameter = "success";
    }
}

class MainClass {
    public static void Main(string[] args) {
            string s = "failed";
        End e = new End(ref s);
        Console.WriteLine("After: {0}", s);
    }
}

Output is:

Inside: failed
After: failed

How do I get “success” on the console?

Thanks in advance,
dijxtra

Answer 1

There are really two issues here.

One, as the other posters have said, you can’t strictly do what you’re looking to do (as you may be able to with C and the like). However – the behavior and intent are still readily workable in C# – you just have to do it the C# way.

The other issue is your unfortunate attempt to try and use strings – which are, as one of the other posters mentioned – immutable – and by definition get copied around.

So, having said that, your code can easily be converted to this, which I think does do what you want:

public class End
{
    public StringBuilder parameter;

    public End(StringBuilder parameter)
    {
        this.parameter = parameter;
        this.Init();
        Console.WriteLine("Inside: {0}", parameter);
    }

    public void Init()
    {
        this.parameter.Clear();
        this.parameter.Append("success");
    }
}

class MainClass
{
    public static void Main(string[] args)
    {
        StringBuilder s = new StringBuilder("failed");
        End e = new End(s);
        Console.WriteLine("After: {0}", s);
    }
}