c# - "this" keyword type when called on an object of derived class from base class -

if have this:

class base {     public void write()     {      if (this derived)       {          this.name();//calls name method of base class i.e. prints base         ((derived)this).name();//calls derived method i.e prints derived        }      else       {         this.name();       }     }      public void name()     {         return "base";     } }  class derived : base {     public new void name()     {         return "derived";     } } 

and use following code call it,

derived v= new derived(); v.write(); // prints base 

then name method of base class gets called. actual type of this keyword in write method? if of derived type(as program control enters first if block in write method) calling base name method, , why explicit casting,(derived)this, change call name method of derived class?

this of derived class type.

the reason why in call this.name(); calls base class name() method because name not defined virtual method, being linked in compile time when compiler knows nothing actual type of this have @ point.

one more note regarding code above. in product code referring derived class base class explicitly bad practice breaks 1 of oop principles base class should not aware classes inherit it. however, assuming code above used c++ investigation of course ok.