430 questions
1
vote
2
answers
196
views
What does the presence of the keyword `virtual` really do in the context of inheritance?
There are lots of posts on the internet about virtual inheritance in C++.
Typically these posts say something like this:
Virtual inheritance solves the Diamond Inheritance Problem
Virtual inheritance ...
- 18.6k
5
votes
1
answer
206
views
Why the keyword "virtual" is used in classes on whose it has no effect?
Consider the following C++ code:
class A
{
public:
int i;
}
class B: virtual public A{};
class C: virtual public A{};
class D: public B, public C{};
int main()
{
D obj;
obj.i = 0;
...
- 203
16
votes
1
answer
534
views
Copying virtual base class results in losing shared_ptr owned object
A colleague at work showed me this program:
#include <iostream>
#include <memory>
struct A {
std::shared_ptr<int> u{ new int };
};
struct B : virtual A {};
struct C : virtual A ...
- 24.1k
-1
votes
2
answers
110
views
What is the difference between (this->*&A::main)(); and this->A::main(); in C++ when dealing with virtual functions? [duplicate]
I'm trying to understand the difference between two ways of calling a function in C++, especially when dealing with virtual functions. Here is a simple code example:
#include <iostream>
class A ...
1
vote
1
answer
94
views
c++ static_cast to virtual base in runtime
Suppose we have such code:
struct Granny {
int g;
};
struct Mom : virtual Granny {
int m;
};
struct Son : Mom {
int s;
};
int main() {
int x;
std::cin >> x;
Mom* mom = (x ? new Son :...
- 13
1
vote
1
answer
98
views
Breaking one leg of diamond inheritance problem: alternatives?
I am contributing some pieces to a large software project in C++. Here's a problem I'm running into.
We already have in the repository
(1) A.h
class A : public X, public Y, public Z
{
...
}
(2) B....
- 41
0
votes
0
answers
63
views
Where to place virtual base class copy assignment operator in derived class copy assignment operator?
In an old closed-source codebase I came across a comment where the author suggests placing virtual base class copy assignment after those of immediate base classes or that it can result in "...
- 1
2
votes
1
answer
72
views
How can I inherit from two classes with the same non-virtual grandparent classes?
Suppose I have four classes A, B, C and D:
class A {
public:
float someData;
float someFunc();
}
class B : public A {
public:
float someOtherData;
float someOtherFunc();
}
class C : ...
1
vote
2
answers
152
views
When should constructor of virtual base class be called?
Consider the following example:
struct Grandpa {
Grandpa(int x) {}
};
struct Dad : Grandpa {
Dad(int y) : Grandpa(15) {}
};
struct Son : Dad {
Son(int z) : Dad(z) {}
};
int main () {
...
- 531
0
votes
0
answers
72
views
If I inherit some attributes from father's pure virtual class and want to implement them in main, do I have to redefine them in the inherited class?
If I inherit some attributes from my father's pure virtual class and want to implement them in main, do I have to redefine them in the inherited class?
This is pure virtual class Father with ...
- 31
0
votes
0
answers
44
views
passing a variable and its value from one class to another through inheritance c#
I want to use inheritance when calculating the area and volume of a cone. I have a circle class whose variables I want to use. I don’t understand why the area value is not transferred and calculated ...
0
votes
1
answer
116
views
Why do shared_ptr and unique_ptr have different behavior when dtors are not virtual?
So, I know that not making polymorphic classes destructors virtual will lead to undefined behavior, and the correct fix to this is to make them virtual. With that being said, why does shared_ptr "...
- 23
2
votes
3
answers
73
views
Mixing Templates, Multiple Inheritance, and non-Default Constructor
I have a base class that implements some functionality, and a template class that virtually extends it. The base class has a non-default constructor since it requires some configuration data. The ...
- 116k
0
votes
2
answers
90
views
virtual multiple inheritance constructor
I'm working on a C++ code example that uses virtual inheritance and multiple inheritance. In my code, I've noticed that I have to call the constructor of the Base class in each derived class, even ...
- 23
0
votes
0
answers
48
views
Create diferent childs struct that expand a function of a parent struct, and pass the child object in another function. C++
I'm creating diferent Child Structs with a diferent implementation of a function, starting with a base Parent function.
I want a general reference to call the function of a Child in another struct as ...
