computer science lab

We're going to do an inventory management system.  In the real world, this would use a database, not a file.  Inventory contains

• item names (or description), like "socks, - red" or "socks - blue".  Thius has to be a character string that WILL include spaces.
• item numbers that are unique to the item, similar to UPC codes, like 121821 or 128122.  These are usually character strings.
• a price, like 4.99, a double.
• a quantity on hand, like 13, an integer.

Your code need to have the following features, all accessible from a menu.

• Add a new inventory item to the data in memory.  You'll type in the inventory number, description, quantity and price.  This will also update the number of items on the menu screen. 
• List the inventory on the screen in neat columns.  Display it in chucks of 15 items with a pause in between.
• Search the inventory for an item by inventory number.   If found, print the stored info, otherwise print 'not found'.
• Calculate the total value on hand. The sum is the accumulation of all the (quantities * prices).
• Save what's in memory to the disk
• Overwrite what's in memory from the disk

The way your work this is you'll load a file, add, search, etc, then write it back to disk. 

Ideas:

• An array of objects works nicely if you read ahead, although this isn't required, see my code below (sorry about the indenting).

Here's a sample menu:

===========================
1) Add an item to memory
2) Search memory for an item
3) List what's in memory
4) Total value on hand
5) Save to a file
6) Read in from a file

0) Exit Program
56 items stored

#include <iostream>
#include <fstream>
#include <cstdlib>

using namespace std;

class invItem
{
 public:
 string name;
 string number;
 double price;
 int quantity;
};

void printItem(invItem someitem);

int main()
{
 /// read in one record
 string itemName;
 string itemNumber;
 double itemPrice;
 int itemQuantity;

 /// read in a single record from a file
 string inputBuffer;
 ifstream invFile("invent1.txt"); /// declares and opens

getline(invFile, itemName);
 getline(invFile, itemNumber);
 getline(invFile, inputBuffer);
 itemPrice = atof(inputBuffer.c_str());
 getline(invFile, inputBuffer);
 itemQuantity = atoi(inputBuffer.c_str());

cout << "Item = " << itemName << "[" << itemNumber <<"]" << endl;
 cout << "Quantity = " << itemQuantity << " @ " << itemPrice
 << " = " << itemPrice * itemQuantity;
 invFile.close();

/// write a single record to a file
 ofstream invOutFile("invent1.txt", ios::app); /// declare and open for append
 invOutFile << "White Sox" << endl;
 invOutFile << "82452374293742" << endl;
 invOutFile << 6.99 << endl;
 invOutFile << 20 << endl;
 invOutFile.close();

/// build a single invItem object
 invItem someitem;
 someitem.name="Green Socks";
 someitem.number="5435234523452345";
 someitem.price=5.99;
 someitem.quantity=67;
 printItem(someitem);

/// build an array of invItem objects and save one to disk
 invItem items[1000];
 items[0].name="Yellow Socks";
 items[0].number="25435567456723452345";
 items[0].price=7.99;
 items[0].quantity=27;
 printItem(items[0]);
 ofstream invOutFile2("invent1.txt", ios::app); /// declare and open for append
 invOutFile2 << items[0].name << endl;
 invOutFile2 << items[0].number << endl;
 invOutFile2 << items[0].price << endl;
 invOutFile2 << items[0].quantity<< endl;
 invOutFile2.close();

return 0;
}

void printItem(invItem someitem)
{
 cout << "Item = " << someitem.name << "[" << someitem.number <<"]" << endl;
 cout << "Quantity = " << someitem.quantity << " @ " << someitem.price
 << " = " << someitem.price * someitem.quantity << endl;

}