Classes problem

This is a discussion on Classes problem within the C++ Programming forums, part of the General Programming Boards category; i need help with this code...i know whats wrong, but i just need to know what i need to do ...

  1. #1
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    Question Classes problem

    i need help with this code...i know whats wrong, but i just need to know what i need to do to fix it. i dont want the answer, just what i need to do.

    Code:
    #include<iostream.h>
    
    class GroceryItem
    {
    	private:
    		int stockNum;
    		double priceEach;
    		int quantity;
    		double totalValue;
    		void calculateTotalValue();
    
    	public:
    		void setStockNum();
    		void setPriceEach();
    		void setQuantity();
    		void displayGroceryItem();
    };
    
    void GroceryItem::setStockNum()
    {	
    	cout<<"Enter the Stock Number: ";
    	cin>>stockNum;
    
    };
    void GroceryItem::setPriceEach()
    {
    	cout<<"Enter the price: ";
    	cin>>priceEach;
    };
    void GroceryItem::setQuantity()
    {
    	cout<<"Enter the quantity in stock: ";
    	cin>>quantity;
    };
    void GroceryItem::calculateTotalValue()
    {
    	totalValue=priceEach*quantity;
    };
    void GroceryItem::displayGroceryItem()
    {
    	cout<<"Item #"<<stockNum<<" Price: "<<priceEach<<endl;
    	cout<<"Quantity in stock: "<<quantity<<" Value: "<<totalValue;
    };
    
    void main()
    {
    
    
    
    	GroceryItem anItem;
    	void setStockNum();
    	void setPriceEach();
    	void setQuantity();
    	void calculateTotalValue();
    	void displayGroceryItem();
    
    
    
    
    
    	anItem.setStockNum();
    	anItem.setPriceEach();
    	anItem.setQuantity();
    	anItem.calculateTotalValue();
    	anItem.displayGroceryItem(stockNum, priceEach, quantity, totalValue);
    
    }

  2. #2
    End Of Line Hammer's Avatar
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    >>.i know whats wrong
    What makes you think that? Be more descriptive with your questions, and people will be able to help you better. Simply expecting someone to read a program and guess at what they think you're complaining about isn't the right way to ask for help.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  3. #3
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    the last 2 lines have errors saying that the the variables are unidentifiable and that the calculatetotalvalue cannot access private variables

  4. #4
    Registered User major_small's Avatar
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    don't read this if you don't want the answer

    you need to watch the scope:
    Code:
    	GroceryItem anItem;
    	void setStockNum();
    	void setPriceEach();
    	void setQuantity();
    	void calculateTotalValue();
    	void displayGroceryItem();
    you should keep the first line, but get rid of the rest...

    and in the scope your using, you never set up a prototype for:
    Code:
    displayGroceryItem(int,double,int,double);
    just fix the first codebit i gave you and your problems may go away...
    Last edited by major_small; 10-27-2003 at 08:32 PM.
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  5. #5
    Registered User jlou's Avatar
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    What to do? Some thoughts:
    1. Bummer that you haven't been able to get a newer book (I assume). You are getting in to a couple of bad habits which may not be the end of the world, but make many people cringe every time you ask for help here (void main() and <iostream.h>).
    2. Look at the errors you get when compiling. You should be able to figure out how to fix them by what they say and what line they refer to. The first one is probably something like:

      'calculateTotalValue' : cannot access private member declared in class 'GroceryItem'

      That means that you are trying to access a private member called "calculateTotalValue". To fix it, either make it public so you can call it from outside the class, or don't call it from outside the class at all (the first option seems more appropriate for you).

      The other errors are probably like:

      'stockNum' : undeclared identifier

      That means that the compiler doesn't recognize the variable stockNum. You have a variable called stockNum, but it is inside your class and it is private. In this case, if you look at the line the error refers to, the question is whether you even need that variable there. If you look at the declaration for the function you are calling, it doesn't take any parameters. Maybe you changed it but forgot to remove the arguments when you called it in main?
    Seriously, you should work on your problem solving skills so that you can fix these errors. Maybe you tried many things, but if you don't make it look like you made an effort when asking for help, you will normally get less sympathy from people here.

  6. #6
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    im not so great at this stuff, but since i did the whole GroceryItem::DisplayGroceryItem, and anItem.DisplayGroceryItem, shouldn't they work with the variables in that class?
    Last edited by ForlornOdium; 10-27-2003 at 09:30 PM.

  7. #7
    Registered User major_small's Avatar
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    yeah, but like i said before, you need to pay attention to scope:
    Code:
    	void setStockNum();
    	void setPriceEach();
    	void setQuantity();
    	void calculateTotalValue();
    	void displayGroceryItem();
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