C# - Similar as string constructor but can't return result

Question

okay guys, i'm new in C# programming, today i was trying to create constructor which will be like a String constructor but the problem is that i have to return the result after i use it, but as i know constructora can't have return type and can't be static

using System;


class StringA {
  public StringA(char x, int y) {
    string res = "";
    string ConvertedChar = Convert.ToString(x);

    for (int i = 0; i < y; i++) {
      res += ConvertedChar;
    }
    // How to return string res?
  }

}
class MainClass {
  static void Main() {
    Console.WriteLine(new StringA('B', 15));
  }
}

Answer 1

What you could do is to override the ToString() Method of your class StringA.

    class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine(new StringA('B', 15));
        Console.Read();
    }
}


class StringA
{

    string res = "";

    public StringA(char x, int y)
    {
        string ConvertedChar = Convert.ToString(x);

        for (int i = 0; i < y; i++)
        {
            res += ConvertedChar;
        }
    }

    public override string ToString()
    {
        return res;
    }

}

Answer 2

Are you looking for a static factory method?

public static string CreateRepeatedString(char x, int y) {
   return new string(x, y);
}

Answer 3

You could use keyword out in following way:

class StringA
{
    public StringA(char x, int y, out string res)
    {
        res = "";
        string ConvertedChar = Convert.ToString(x);

        for (int i = 0; i < y; i++)
        {
            res += ConvertedChar;
        }
        // or even shorter
        // res = new string(x, y);
      }
}

Then you can pass some string to constrctor and get it's value changed in constructor. Then you can use it:

class MainClass
{
    static void Main()
    {
        string res;
        Console.WriteLine(new StringA('B', 15, out res));
    }
}

Answer 4

Perhaps you can create a public accessor for your class, or would you rather need a static factory method as @Joey stated in his answer ?

See below example:

using System;

namespace YourNamespace {
  class StringA {

    private string privateVal = "";
    public string PublicVal {
      get {
        return this.privateVal;
      }
      set {
        this.privateVal = value;
      }
    }
    public StringA(char x, int y) {
      string res = "";
      string ConvertedChar = Convert.ToString(x);

      for (int i = 0; i < y; i++) {
        res += ConvertedChar;
      }
      // How to return string res?
      this.privateVal = res; //assign res to your accessor
    }

  }
  class MainClass {
    static void Main() {
      //then you can access the public property
      Console.WriteLine(new StringA('B', 15).PublicVal);
    }
  }
}

Answer 5

Besides the above answers, you can also add an implicit operator

class StringA
{
    private readonly string instance;
    public StringA(char x, int y)
    {
        string res = "";
        string ConvertedChar = Convert.ToString(x);

        for (int i = 0; i<y; i++)
        {
            res += ConvertedChar;
        }
        this.instance = res;
    }

    public static implicit operator string(StringA d) => d.instance;   
}  

This can then be used as:

string str = new StringA('x', 10);
Console.WriteLine(new StringA('y',100));