A reference constriant : Type constaint : Generic C# Examples

    
using  System;  
  
class  MyClass  {  
}  
  
class  Test<T>  where  T  :  class  {  
    T  obj;  
  
    public  Test()  {  
        //  Here  T  must  be  a  reference  type,  
        //  which  can  be  assigned  the  value  null.  
        obj  =  null;  
    }  
}  
  
class  MainClass  {  
    public  static  void  Main()  {  
        //  The  following  is  OK  because  MyClass  is  a  class.  
        Test<MyClass>  x  =  new  Test<MyClass>();  
  
        //  The  next  line  is  in  error  because  int  is  a  value  type.  
        //  Test<int>  y  =  new  Test<int>();  
    }  
}