+ 3
C++ supports multiple inheritance. What is the 'diamond problem' that can occur with multiple inheritance? Give an example.
6 odpowiedzi
+ 1
Not need example it is very easy problem. You have class A, then you habe class B and C inherit from A and classD inherit from B and C.
In this case diagram will be diamong(name of problem) in all classes you have some virtual function f()
So when you create instance of class D and call finction f, the compiler do not know which of way construct d:f-c:f-a:f or d:f-b:f-a:f.(imagine that compiler need construct way).
So for this need use virtual inheritence, and in this case it will be use first declarated parent class name
+ 5
the problems that arises due to multiple inheritance is the diamond problem. A classical illustration of this is given by Bjarne Stroustrup (the creator of C++) in the following example:
class storable class inherited by transmitter and receiver classes
{
public:
storable(const char*);
virtual void read();
virtual void write();
virtual ~storable();
private:}
class transmitter: public storable
{ public:
void write();}
class receiver: public storable
{ public:
void read();
}
class radio: public transmitter, public receiver
{
public:
void read();
}
Since both transmitter and receiver classes are using the method write() from the base class, when calling the method write() from a radio object the call is ambiguous; the compiler can't know which implementation of write() to use, the one from the transmitter class or the one from the receiver class
https://www.cprogramming.com/tutorial/virtual_inheritance.html
+ 2
Diamond problem solve occured when
Two base classes of a class have common superclass
A
/. \. D will get common member of
B. C. B,C twice which are of A
\. /. And produce a ambiguous
D. Situation