using System;

using System.Collections;

using System.Collections.Generic;

public class Program

{

  public static void Main()

  {

    IDictionary myDictionary = new Dictionary<string, int>();

​

    myDictionary.Add("a", 1);

    myDictionary.Add("b", 2);

    myDictionary.Add("c", 3);

​

    Console.WriteLine(myDictionary.ToStringFormatted());

  }

}

​

static public class IDictionaryHelper

{

  static public string ToStringFormatted(this IDictionary dictionary, char separator = ';')

  {

    string result = "";

    foreach (DictionaryEntry item in dictionary)

      result += $"{item.Key.ToString()}={item.Value.ToString()}{separator}";

    return result.TrimEnd(separator);

  }

}