Re: Virtual function behaviour
dragoncoder wrote:
I was just playing around wrote this code.
sundev1:/home/ptiwary/rnd $ cat a1.cpp
#include <iostream>
using namespace std;
class Base
{
public:
virtual void foo() { cout << "In Base::foo()" << endl; bar();}
private:
void bar() { cout << "In Base::bar()" << endl; }
};
class Der1: public Base
{
public:
virtual void foo() { cout << "In Der1::foo()" << endl; bar();}
private:
void bar() { cout << "In Der1::bar()" << endl; }
};
class Der2: public Base
{
public:
virtual void foo() { cout << "In Der2::foo()" << endl; bar();}
private:
void bar() { cout << "In Der2::bar()" << endl; }
};
int main()
{
Base* b1 = new Base();
Base* b2 = new Der1();
Base* b3 = new Der2();
b1->foo();
b2->foo();
b3->foo();
return 0;
}
sundev1:/home/ptiwary/rnd $ g++ a1.cpp
sundev1:/home/ptiwary/rnd $ ./a.out
In Base::foo()
In Base::bar()
In Der1::foo()
In Der1::bar()
In Der2::foo()
In Der2::bar()
I have 2 questions regarding this.
1. Is the behaviour correct? Because someone told me I need to make
bar() also virtual to get the effect.
No, the 'bar' resolved "statically" (as 'this->bar') in each of the
'foo' functions.
2. What is the deal with private virtual functions? Even if I make
bar() virtual, as its private, it won't be accessible from the derived
classes Der1 and Der2 so it does not make any sense having private
virtual functions. Am I right?
Access specifiers and virtuality are orthogonal. IOW, it does not
matter what access specifiers virtual functions have to establish
which of them overrides which.
V
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