Part 34 - C# Tutorial - Problems of multiple class inheritance.avi Video

hello welcome to present technologies
I'm venket this is part thirty four in
this session we'll understand the
problems of multiple class inheritance
to understand the session properly we
need to understand inheritance
polymorphism difference between method
overriding and method hiding and you can
check these in 521 523 and part 24 of
this video series we know that si chef
doesn't support multiple class
inheritance and there is a specific
reason behind that and that's what we'll
be exploring in this session let's flip
through a demo let's say I have a class
called class a and this is got a virtual
method public which will void print and
for this virtual method class a is going
to provide a default implementation so
let's say a implementation all right I'm
going to have another class class B
which is going to inherit from a now we
know that if we mark a method as virtual
in the base class that means the derived
class can override that implementation
so Class B is going to override the
print method so override the print
method and here that's going to say
class control the red line B
implementation so B class is
implementing this okay I'm going to have
another class called class C and this
class is also going to inherit from
Class A and then this class is also
overriding the virtual method which it
has inherited from Class A
and finally I'm going to have another
class Class D and this time this class
is going to inherit from both P and C
and we know that c-sharp doesn't support
multiple class inheritance I mean this
line will actually through a compiler
error but for now let's assume that
c-sharp does support multiple class
inheritance okay
and then we will see the problem with
that alright so if you understood this
properly until now the situation is
something like this we have Class A the
super base class which has got a virtual
print method so if you look at this one
in Class A we have this virtual print
method that's the super base class and
from this class a book Class B and Class
C are driving so Class B and Class C is
deriving from Class A and both of them
override the virtual print method which
they have ripped which they have
inherited from Class A and Class D is
inheriting from both Class B and C but
Class D did over I the print method so
that's what is the situation so B and C
inheriting from a and both of them has
over done the print method and whereas
if we look at class D it inherits from
both B and C but then over I the print
method now if somebody creates an
instance of class D like this D is equal
to nu D and if they say D dot print now
which version of the overridden print
method should D invoke should invoke the
print method from B class or from C
class so there is definitely this
ambiguity and this is what is called as
diamond problem and the reason why they
have given it diamond problem as the
name is because of the shape it forms
they have this class a and the class B
and C inherits from that Class A and
Class B and C override the virtual
method they have in
from Class A but Class D which is going
to be inherited from Class B and C does
not overwrite that virtual method as a
result if somebody creates an instance
with this class D and invoke that
overridden method which version of the
overridden method should be called class
B's overridden version or class C's
overridden version so this is the
ambiguity and and this is called as time
and problem and if you look at this
slide it's exactly this the same code
that we have looked at just now on this
slide you can see resources for asp.net
and C sharp interview questions that's
it for today
thank you for listening have a great day