interfaces.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Reflection;

namespace Program {
    interface Ifc1 { void Print(string s); }
    interface Ifc2 { void Print(string s); }
    interface Ifc3 : Ifc1 { void Print(string s); }

    class A : Ifc1, Ifc2 {
        public void Print(string s) { Console.WriteLine("Called with: {0}", s); }
        void Ifc1.Print(string s) { Console.WriteLine("Ifc1: {0}", s); }
        void Ifc2.Print(string s) { Console.WriteLine("Ifc2: {0}", s); }
    }

    class B : A {
        public B() {
            Print("B");
            ((Ifc1)this).Print("B");
        }
    }

    class C : B, Ifc3 {
        void Ifc3.Print(string s) { Console.WriteLine("Ifc3: {0}", s); }
    }

    class TestCases {
        public static void MultiInterface() {
            var o = new C();
            Ifc1 i = o as Ifc1; // Ifc1 i = (Ifc1)o
            Ifc2 j = o as Ifc2; // Ifc2 j = (Ifc2)o
            Ifc3 k = o as Ifc3;

            o.Print("object");
            if (i != null && j != null && k != null) {
                i.Print("iface 1");
                j.Print("iface 2");
                k.Print("iface 3");
                ((Ifc3)(A)o).Print("yo");
                ((A)(Ifc3)o).Print("jo");
            }
        }

        public static void BaseImplementation() {
            var o = new B();
            o.Print("object");
        }

    }

    class Program {
        static void Main(string[] args) {
            TestCases.MultiInterface();
            // TestCases.BaseImplementation();
            Console.Read();
        }
    }
}