What is the difference between the two classes


//first type 
class a ;
endclass 

class b extends class a;
endclass
//second type
class a;
endclass
class b;
a a1;
endclass

could you please let me know the what is the diffrence between first type and second type

In reply to srbeeram:

This is one of the fundamental concepts of OOP. Please see one of the many courses on SystemVerilog OOP.

http://go.mentor.com/SV-OOP