Default parameters in c# 4

I just read about a very cool feature of "default parameter" in a webblog of a microsoft employee.I just want that others should also be aware of this feature so,I am included this in my post also.

Presently in c# 3.5 we all are just using the function overloading in order to provide the default or optional parameter functionality.e.g

public class oldclass
  {
      public string A{ get; set; }
      public string B{ get; set; }
      public string C{ get; set; }
    
      public oldclass(string a)
      {
          A= a;
          B= "B";
          C= string.Empty;
      }
      public oldclass(string a, string b)
      {     
          A= a;
          B= b;
          C= string.Empty;
       
      }
      public oldclass(string a, string b, string c)
      {
          A= a;
          B= b;
          C= c;
      }
  }

But now in c# 4 what we do is:-

public class newclass
  {
      public string A{ get; set; }
      public string B{ get; set; }
      public string C{ get; set; }
            
      public newclass(string a, string b="B", string c=string.Empty)
      {
          A= a;
          B= b;
          C= c;
      }
  }

if we initialize constructor using-> new newclass("A");
then values for A="A",B="B"and C="".

So,Its quite cool to include this feature in c# 4 so that now,we don't have to use function overloading for getting functionality of optional parameters.