Using pointers in class - c++

Question

Hi all I have an unusual problem here. I wrote a moneychanger class that determines the number of bills and coins that are given as change, based on the total amount for a purchase and the amount of money given for the purchase. For example if you were going to buy something for $12.04 and gave a $20 dollar bill you would receive $7.96 in change.
the output would be:
0 twenty dollar bill(s)
0 ten dollar bill(s)
1 5 dollar bill(s)
2 1 dollar bills(s)
3 quarter(s)
2 dime(s)
1 penny(s)
now the thing is that i have to return the numbers of each bill and coin using pointers or references.
my program has two functions a GetBills which uses pointers to integers to return the number of $20, $10, $5, and $1 bills that are needed for the change.
the other is a GetCoins which again uses pointers to integers to return the number of quarters dimes, nickels, and pennies that are needed for the change.
My problem is this. my GetBills is not storing any values in the pointers but my GetCoins is. if i enter 12.04 for purchase price and 20.00 given amount
my output is:
0 twenty dollar bill(s)
0 ten dollar bill(s)
0 5 dollar bill(s)
0 1 dollar bills(s)
3 quarter(s)
2 dime(s)
1 penny(s)
so as you can see some the values for the coins good but not for the bills. What could be causing my pointers in my GetBills to not store the proper values?
here's my shortened code:
MoneyChanger.h
class MoneyChanger
{
private:
double amountP, amountG, totalChange;
int twenty, ten, five, one, change;
int quarter, dime, nickel, penny;
public:
void GetBills(int *twenties, int *tens, int *fives, int *ones);
void GetCoins(int *quarters, int *dimes, int *nickels, int *pennies);
};
MoneyChanger.cpp
void MoneyChanger::setData(double pp, double given)
{
amountP = pp;
amountG = given;
CalcChange();
}
void MoneyChanger::CalcChange()
{
while(totalChange >= 20){totalChange = totalChange-20; twenty++;}
while(totalChange >= 10){totalChange = totalChange-10; ten++;}
while(totalChange >= 5){totalChange = totalChange-5; five++;}
while(totalChange >= 1){totalChange = totalChange-1; one++;}
while(totalChange >= .25){totalChange = totalChange-.25; quarter++;}
while(totalChange >= .10){totalChange = totalChange-.10; dime++;}
while(totalChange >= .05){totalChange = totalChange-.05; nickel++;}
while(totalChange >= .01){totalChange = totalChange-.01; penny++;}
}
double MoneyChanger::GetTotalChange()
{
totalChange = amountG - amountP;
return totalChange;
}
void MoneyChanger::GetBills(int *twenties, int *tens, int *fives, int *ones)
{
*twenties = twenty;
*tens = ten;
*fives = five;
*ones = one;
CalcChange();
}
void MoneyChanger::GetCoins(int *quarters, int *dimes, int *nickels, int *pennies)
{
*quarters = quarter;
*dimes = dime;
*nickels = nickel;
*pennies = penny;
CalcChange();
}
Main.cpp
int main()
{
MoneyChanger mc;
int twenties, tens, fives, ones, quarter, dimes, nickels, pennies;
double purchase, given;
cout<<"please enter total cost of purchase: ";
cin>>purchase;
cin.ignore();
cout<<"\nplease enter amount given: ";
cin>>given;
mc.setData(purchase, given);
cin.ignore();
cout<<"Your change is: "<<mc.GetTotalChange()<<"\n\n";
mc.GetBills(&twenties, &tens, &fives, &ones);
mc.GetCoins(&quarter, &dimes, &nickels, &pennies);
cout<<twenties<<" twenty dollar bill(s)"<<endl;
cout<<tens<<" ten dollar bill(s)"<<endl;
cout<<fives<<" five dollar bill(s)"<<endl;
cout<<ones<<" one dollar bill(s)"<<endl;
cout<<quarter<<" quarter(s)"<<endl;
cout<<dimes<<" dime(s)"<<endl;
cout<<nickels<<" nickel(s)"<<endl;
cout<<pennies<<" penny(s)"<<endl;
return 0;
}

Answer 1

I think your problem is in GetBills and GetCoins the CalcChange function should be called first, before assignment. Assuming you've initialized your bills/coins member variables to 0, the first call to GetBills will set all the passed in bills to 0. Your function will then compute what the values of bills and coins should be. In call to GetCoins the coin member variables will have already been set to the correct values from the CalcChange call in GetBills.
I would recommend pulling calcChange out of both of those functions (as multiple calls to it is redundant) and do some thing like this in your main:
cout<<"Your change is: "<<mc.GetTotalChange()<<"\n\n";
mc.calcChange();
mc.GetBills(&twenties, &tens, &fives, &ones);
mc.GetCoins(&quarter, &dimes, &nickels, &pennies);