Program.cs

namespace ReferenceTypes;

class Program
{
    static void Main()
    {
        CopyingReferences();

        Console.WriteLine();
        Console.WriteLine();

        ComparingReferences();

        Console.WriteLine();
        Console.WriteLine();

        ComparingValues();
    }

    internal static void CopyingReferences()
    {
        var c1 = new Counter();
        Counter c2 = c1;
        Console.WriteLine($"c1: {c1.GetNextValue()}");
        Console.WriteLine($"c1: {c1.GetNextValue()}");
        Console.WriteLine($"c1: {c1.GetNextValue()}");

        Console.WriteLine($"c2: {c2.GetNextValue()}");

        Console.WriteLine($"c1: {c1.GetNextValue()}");
    }

    internal static void ComparingReferences()
    {
        var c1 = new Counter();
        c1.GetNextValue();
        Counter c2 = c1;
        var c3 = new Counter();
        c3.GetNextValue();

        Console.WriteLine(c1.Count);
        Console.WriteLine(c2.Count);
        Console.WriteLine(c3.Count);
        Console.WriteLine(c1 == c2);
        Console.WriteLine(c1 == c3);
        Console.WriteLine(c2 == c3);
        Console.WriteLine(object.ReferenceEquals(c1, c2));
        Console.WriteLine(object.ReferenceEquals(c1, c3));
        Console.WriteLine(object.ReferenceEquals(c2, c3));
    }

    // With the default SDK settings, the code analysis rules detect the
    // problem this example illustrates, reporting CA2013 warnings. This
    // particular example makes this mistake on purpose, so we disable the
    // warning.
#pragma warning disable CA2013

    internal static void ComparingValues()
    {
        int c1 = new int();
        c1++;
        int c2 = c1;
        int c3 = new int();
        c3++;

        Console.WriteLine(c1);
        Console.WriteLine(c2);
        Console.WriteLine(c3);
        Console.WriteLine(c1 == c2);
        Console.WriteLine(c1 == c3);
        Console.WriteLine(c2 == c3);
        Console.WriteLine(object.ReferenceEquals(c1, c2));
        Console.WriteLine(object.ReferenceEquals(c1, c3));
        Console.WriteLine(object.ReferenceEquals(c2, c3));
        Console.WriteLine(object.ReferenceEquals(c1, c1));
    }
}