simple base and derived class example [member function override pure virtual function]

Bjarne Stroustrup “Programming Principles and Practice Using C++”
Chapter 14 Drill 7
Using std_lib_facilities.h by Bjarne Stroustrup.

[code language=”cpp”]
// Philipp Siedler
// Bjarne Stroustrup’s PP
// Chapter 14 Drill 7

#include "std_lib_facilities.h"
using namespace std;

class B2
{
public:
virtual void pvf() = 0;
};

class D21 : public B2
{
public:
void pvf() { cout << data << endl; }
string data;
};

class D22 : public B2
{
public:
void pvf() { cout << val << endl; }
int val;
};

void f(B2& b2_ref) {
b2_ref.pvf();
}

int main()
try
{
D21 d21;
d21.data = "hello";
D22 d22;
d22.val = 5;

f(d21);
f(d22);

keep_window_open();
}
catch (exception& e) {
cout << e.what() << endl;
return 1;
}
catch (…) {
cout << "Exiting" << endl;
return 2;
}
[/code]

Output:
hello
5
Please enter a character to exit

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