The following example shows the simple implementation of a pure virtual function: #include <iostream>using namespace std;//The abstract classclass parent{ public: // Pure virtual function virtual void print() = 0;};class child: public parent{ public: void print(){ cout << "Inside Child ...
In the main, we can call `make_sound` on a Pet pointer without knowing at compile time which kind of pet this pointer points at, and at runtime we reach the desired function based on the actual object that is there. We must emphasize that this is a very simple example. For this ...
In the very first example, the object ‘obj_a’ was pointing to the base part of class ‘A’ in class ‘B’. So, when ‘obj_a.fetchClassName()’ was called, the corresponding function of class ‘A’ was called. Now, when the function ‘fetchClassName()’ was made virtual, then th...
However, in every case, we ran up against the problem that the base pointer or reference was only able to call the base version of a function, not a derived version. Here’s a simple example of this behavior: #include <iostream> #include <string_view> class Base { public: std::...
In C++, if you call a virtual function from a constructor or destructor, the compiler calls the instance of the virtual function defined for the class being constructed (for example, Base::SomeVirtFn if called from Base::Base), not the most derived instance. As you sa...
It's simple and clear(下面的规则简单又明快): virtual means exactly and only "this is a new virtual function." virual明确表示而且只用于表示"这是一个新的虚函数" override means exactly and only "this is a non-final overrider." overide明确表示而且只表示“这不是最终覆盖者” ...
class C : public A, public B { using A::foo; }; int main() { B b; b.foo(); // OK: B::foo() C c; c.foo(); // error: A::foo() or private member in class 'C' return 0; } Virtual Functions When we talk aboutvirtual functionorvirtual method, it's always in the co...
The above example will cause the following line to be printed out: I am an Manager However, if we remove the virtual keyword, then when we call the display function using the Base Class pointer (e1), then thedisplay()function of the Base Class will be called. Instead of thedisplay()fun...
It's simple and clear(下面的规则简单又明快): virtual means exactly and only "this is a new virtual function." virual明确表示而且只用于表示"这是一个新的虚函数" override means exactly and only "this is a non-final overrider." overide明确表示而且只表示“这不是最终覆盖者” ...
virtual: the call is indirect. C++ jocks say the function is bound at runtime, or late-bound (as a opposed to compile time, which is early-bound). If some other A-derived object has a different vtable, the previous code calls the function in that vtable, as my next example shows. ...