a subclass uses the keyword base to invoke a particular subclass constructor : Base : Class C# Examples

    
using  System;

public  class  Class1  {
        public  static  void  Main(string[]  args)  {
                SubClass  sc1  =  new  SubClass();

                SubClass  sc2  =  new  SubClass(1,  2);

        }
}

public  class  BaseClass  {
        public  BaseClass()  {
                Console.WriteLine("Constructing  BaseClass  (default)");
        }
        public  BaseClass(int  i)  {
                Console.WriteLine("Constructing  BaseClass({0})",  i);
        }
}

public  class  SubClass  :  BaseClass  {
        public  SubClass()  {
                Console.WriteLine("Constructing  SubClass  (default)");
        }
        public  SubClass(int  i1,  int  i2)
                :  base(i1)  {
                Console.WriteLine("Constructing  SubClass({0},  {1})",
                                                                                                    i1,  i2);
        }
}