Re: need help in object orientated programming

"osmium" <>
Thu, 10 Jul 2008 11:34:04 -0700
<> wrote:

<extract follows>
I need help on my mini project on object orientated programming. The
question goes like this:
A mini-mart has just installed a bar code reader to improve efficiency
at their checkouts.
Assume that the bar code is to access a file that store the product
descriptions, unit price
and quantity of each product sold in the shop. Assume that there are
only 10 products in
this mini-mart.
The format of the product stored in the file is shown below :
Barcode : a text string of 4 numeric character
Product description : a text string of 20 characters
Unit price : a floating point value
Quantity : an integer
Design the necessary classes and member functions to achieve the
following tasks :
a. Read the list of products available in the mini-mart from a text
b. Allow user to enter the bar code of a product via keyboard and the
purchase during check out.
c. Display the product description, unit price, quantity and the total
cost of all the
products bought by a customer.
d. Update the quantity of each product in stock after a purchase is
e. Write the bar code and product description to a text file if the
level of stock is less
than 10.
f. Continue the program until user press a ?Q? to exit.

Please enlighten me on how can i start to write the program?

<end extract>

We don't know what you have been taught so far, e.g., are you supposed to
use C++ strings or C strings? C arrays or C++ vectors? My guess is that
you are expected to use the C version of things.

Start by defining a struct to hold a record. It is fundamental to most of
the other stuff. You will probably have an array of these structures.

It looks like your instructor got tired of writing before he finished the
specification. There is no means of producing an initial data base (it
wasn't inherited as the scan code is new). There is no means of specifying
the end of one customer and the beginning of another customer. There is no
way of saving the data base at the end of a business day. You might as well
let your imagination take over and finish it per your desires. Sketch the
menu you plan to present to the user. Does it seem complete?

I see only one class, call it DB for data base. It would have a few member
functions; note that there is not a 1:1 correlation between menu items and
member functions. For example, I would subsume 'd' under 'b' and 'e' under

Rather than make an issue of the initial data base, it might be simpler to
just create one with the text editor you use to write programs. So it would
not be a line item on the menu.

Obviously if there are things that don't make sense to you in the
assignment, you are in a bad position to start writing a program. Maybe
the instructor covered some of these things that bother me in class.

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