abstract class error

adam2016 (1529)
Hey guys,

so a pretty beginner exercise but I decided to give it a shot, it's from a book I am currently reading on data structures and algorithms,

the problem I have is I can't instantiate the oneHundred bill class, obviously we can't instantiate the Bill class itself as it's an abstract class but shouldn't I be able to instantiate the oneHundred bill class as I don't provide any pure virtual functions in the class itself rather I just implement the virtual function that is supposed to be implemented which is - virtual string getMakePureVirtualCoin(). but the compiler is telling me I can't instantiate the oneHundred bill class as it's an abstract class, but is isn't, right??


C++\algorithmBookProblems\main.cpp|179|error: invalid new-expression of abstract class type 'OneHundred'|




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146
 
  class Money{

   public:

   string makePureVirtual;
   string name;
   double amount;

   Money(){};
   Money(string name,double amount):name(name),amount(amount){};
   virtual string getMakePureVirtual()=0;
};

// notes / bills

class Bill : public Money{

   public:
       string makePureVirtualBill;
       Bill(){}
       Bill(string name,double amount): Money(name,amount){};
       virtual string getMakePureVirtualBill()=0;

};

class Five : public Bill{

public:
    Five():Bill("five",5){};
};

class Ten : public Bill{

public:
    Ten():Bill("ten",10){};
};

class Twenty : public Bill{

public:
    Twenty():Bill("twenty",20){};
};

class Fifty : public Bill{

public:
    Fifty():Bill("Fifty",50){};
};

class OneHundred : public Bill{

public:
    OneHundred():Bill("one hundred",100){};
    virtual string getMakePureVirtualBill(){ cout << "now a class" << endl;}
};


// coins

class Coin : public Money{

   public:
       string makePureVirtualCoin;
       Coin(){}
       Coin(string name,double amount): Money(name,amount){};
       virtual string getMakePureVirtualCoin()=0;
};

class OneCent : public Coin{

public:
    OneCent():Coin("one Cent",0.01){};
};

class TwoCent : public Coin{

public:
    TwoCent():Coin("two Cent",0.02){};
};

class FiveCent : public Coin{

public:
    FiveCent():Coin("five Cent",0.05){};
};

class TenCent : public Coin{

public:
    TenCent():Coin("ten Cent",0.10){};
};

class TwentyCent : public Coin{

public:
    TwentyCent():Coin("twenty Cent",0.20){};
};

class FiftyCent : public Coin{

public:
    FiftyCent():Coin("fifty Cent",0.50){};
};

class OneEuro : public Coin{

public:
    OneEuro():Coin("one ",1){};
};

class TwoEuro : public Coin{

public:
    TwoEuro():Coin("two",2){};
};


Money* buySomething(int amount,int price){

     vector<Money*> money;

     if(amount < price)
        return NULL;

     double change = amount - price;
     double amountChangePaid = change;

     while(amountChangePaid > 0){

        if(amountChangePaid >= 100){

            amountChangePaid -= 100;
            OneHundred* onehundred = new OneHundred;
            //money.push_back(onehundred);
            continue;
        }

     }

}


int main()
{
    // to do
}


*edit - I forgot to implement the virtual function in the Moneyclass

adding virtual string getMakePureVirtual(){ cout << "2" << endl;} fixed the issue... so far
Last edited on
adam2016 (1529)
so fixed the issue but seems like my change dispenser is leaving me short a couple of cent

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class Money{

   public:

   string makePureVirtual;
   string name;
   double amount;

   Money(){};
   Money(string name,double amount):name(name),amount(amount){};
   virtual string getMakePureVirtual()=0;
};

// notes / bills

class Bill : public Money{

   public:
       string makePureVirtualBill;
       Bill(){}
       Bill(string name,double amount): Money(name,amount){};
       virtual string getMakePureVirtualBill()=0;

};

class Five : public Bill{

public:
    Five():Bill("five",5){};
    virtual string getMakePureVirtualBill(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class Ten : public Bill{

public:
    Ten():Bill("ten",10){};
    virtual string getMakePureVirtualBill(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class Twenty : public Bill{

public:
    Twenty():Bill("twenty",20){};
    virtual string getMakePureVirtualBill(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class Fifty : public Bill{

public:
    Fifty():Bill("Fifty",50){};
    virtual string getMakePureVirtualBill(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class OneHundred : public Bill{

public:
    OneHundred():Bill("one hundred",100){};
    virtual string getMakePureVirtualBill(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};


// coins

class Coin : public Money{

   public:
       string makePureVirtualCoin;
       Coin(){}
       Coin(string name,double amount): Money(name,amount){};
       virtual string getMakePureVirtualCoin()=0;
};

class OneCent : public Coin{

public:
    OneCent():Coin("one Cent",0.01){};
    virtual string getMakePureVirtualCoin(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class TwoCent : public Coin{

public:
    TwoCent():Coin("two Cent",0.02){};
    virtual string getMakePureVirtualCoin(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class FiveCent : public Coin{

public:
    FiveCent():Coin("five Cent",0.05){};
    virtual string getMakePureVirtualCoin(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class TenCent : public Coin{

public:
    TenCent():Coin("ten Cent",0.10){};
    virtual string getMakePureVirtualCoin(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class TwentyCent : public Coin{

public:
    TwentyCent():Coin("twenty Cent",0.20){};
    virtual string getMakePureVirtualCoin(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class FiftyCent : public Coin{

public:
    FiftyCent():Coin("fifty Cent",0.50){};
    virtual string getMakePureVirtualCoin(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class OneEuro : public Coin{

public:
    OneEuro():Coin("one ",1){};
    virtual string getMakePureVirtualCoin(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};

class TwoEuro : public Coin{

public:
    TwoEuro():Coin("two",2){};
    virtual string getMakePureVirtualCoin(){ cout << "now a class" << endl;}
    virtual string getMakePureVirtual(){ cout << "2" << endl;}
};


vector<Money*> buySomething(double amount,double price){

     vector<Money*> money;

     if(amount < price)
        return money;

     double change = amount - price;
     double amountChangePaid = change;

     while(amountChangePaid > 0){

        if(amountChangePaid >= 100){

            amountChangePaid -= 100;
            money.push_back(new OneHundred);
            continue;
        }

        if(amountChangePaid >= 50){

            amountChangePaid -= 50;
            money.push_back(new Fifty);
            continue;
        }

        if(amountChangePaid >= 20){
            amountChangePaid -= 20;
            money.push_back(new Twenty);
            continue;
        }

        if(amountChangePaid >= 10){
            amountChangePaid -= 10;
            money.push_back(new Ten);
            continue;
        }

        if(amountChangePaid >= 2){
            amountChangePaid -= 2;
            money.push_back(new TwoEuro);
            continue;
        }

        if(amountChangePaid >= 1){
            amountChangePaid -= 1;
            money.push_back(new OneEuro);
            continue;
        }

        if(amountChangePaid >= 0.50){
            amountChangePaid -= 0.50;
            money.push_back(new FiftyCent);
            continue;
        }

        if(amountChangePaid >= 0.20){
            amountChangePaid -= 0.20;
            money.push_back(new TwentyCent);
            continue;
        }

        if(amountChangePaid >= 0.10){
            amountChangePaid -= 0.10;
            money.push_back(new TenCent);
            continue;
        }

        if(amountChangePaid >= 0.05){
            amountChangePaid -= 0.05;
            money.push_back(new FiveCent);
            continue;
        }

        if(amountChangePaid >= 0.02){
            amountChangePaid -= 0.02;
            money.push_back(new TwoCent);
            continue;
        }

        if(amountChangePaid >= 0.01){
            amountChangePaid -= 0.01;
            money.push_back(new OneCent);
            continue;
        }
     }
     return money;
}


int main()
{

    vector<Money*> money = buySomething(200.42,88.55);

    for(int i = 0; i < money.size(); i++){

        cout << money.at(i)->name << endl;
    }
    return 0;
}


200.42 - 88.55 seems to give me back almost the correct amount of change but leaves me 7 cents short.





one hundred
ten
one
fifty Cent
twenty Cent
ten Cent

Last edited on
adam2016 (1529)
*edit again, spotted the bug I subtracted 10 instead of 0.10 now fixed, but now the while loop seems to infinitely loop, seems like it gets stuck on 0.01 cent and won't subtract any further to 0 .

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vector<Money*> buySomething(double amount,double price){

     vector<Money*> money;

     if(amount < price)
        return money;

     double change = amount - price;
     double amountChangePaid = change;

     while(amountChangePaid > 0){

        cout << amountChangePaid << endl;

        if(amountChangePaid >= 100){

            amountChangePaid -= 100;
            money.push_back(new OneHundred);
            continue;
        }

        if(amountChangePaid >= 50){

            amountChangePaid -= 50;
            money.push_back(new Fifty);
            continue;
        }

        if(amountChangePaid >= 20){
            amountChangePaid -= 20;
            money.push_back(new Twenty);
            continue;
        }

        if(amountChangePaid >= 10){
            amountChangePaid -= 10;
            money.push_back(new Ten);
            continue;
        }

        if(amountChangePaid >= 2){
            amountChangePaid -= 2;
            money.push_back(new TwoEuro);
            continue;
        }

        if(amountChangePaid >= 1){
            amountChangePaid -= 1;
            money.push_back(new OneEuro);
            continue;
        }

        if(amountChangePaid >= 0.50){
            amountChangePaid -= 0.50;
            money.push_back(new FiftyCent);
            continue;
        }

        if(amountChangePaid >= 0.20){
            amountChangePaid -= 0.20;
            money.push_back(new TwentyCent);
            continue;
        }

        if(amountChangePaid >= 0.10){
            amountChangePaid -= 0.10;
            money.push_back(new TenCent);
            continue;
        }

        if(amountChangePaid >= 0.05){
            amountChangePaid -= 0.05;
            money.push_back(new FiveCent);
            continue;
        }

        if(amountChangePaid >= 0.02){
            amountChangePaid -= 0.02;
            money.push_back(new TwoCent);
            continue;
        }

        if(amountChangePaid >= 0.01){
            amountChangePaid -= 0.01;
            money.push_back(new OneCent);
            break;
        }
        cout << amountChangePaid << endl;
     }
     return money;
}






111.87
11.87
1.87
0.87
0.37
0.17
0.07
0.02
one hundred
ten
one
fifty Cent
twenty Cent
ten Cent
five Cent
one Cent


seems like it never gets to two cent? and when it does hit the if statement in which it checks if the amountChangePaid is greater than or equal to 2 it seems like the if statement is skipped.

anybody know why the while loop is not ending??

thanks
Last edited on
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