Copy constructor in polymorphism in C# -

please first take @ simple code;

this base class:

public class baseclass {     public baseclass()     {     }      public baseclass(baseclass b)     {     }      public virtual string getmsg()     {         return "base";     } } 

and derived one:

public class drivenclass : baseclass {     public string msg { get; set; }      public drivenclass(string msg)     {         msg = msg;     }      public drivenclass(drivenclass d)     {         msg = d.msg;     }      public override string getmsg()     {         return  msg;     } } 

and test:

public partial class form1 : form {     public form1()     {         initializecomponent();     }      public baseclass b { get; set; }     public drivenclass d { get; set; }      private void button1_click(object sender, eventargs e)     {         d = new drivenclass("driven");         b = new baseclass(d);         messagebox.show("b:" + b.getmsg() + "\nd:" + d.getmsg());     } } 

now question should b = new baseclass(d); works b = new drivenclass(d); ?

i'm using in polymorphism , use 1 copy-constructor instead of different driven ones.

i want output :

driven driven 

but it's :

base driven 

you can use overridden virtual copy method instead of copy constructor.

public class baseclass {     public baseclass()     {     }      public virtual baseclass shallowcopy()     {         return new baseclass();     }      public virtual string getmsg()     {         return "base";     } }  public class drivenclass : baseclass {     public string msg { get; set; }      public drivenclass(string msg)     {         msg = msg;     }      public override baseclass shallowcopy() {         return new drivenclass(this.msg);     }      public override string getmsg()     {         return  msg;     } } 

then call this:

d = new drivenclass("driven"); b = d.shallowcopy(); 

this work because calling virtual method calls actual overriden implementation in subclass, when called baseclass interface.