C# 0 The Complete Reference

PART I

C h a p t e r   1 4 :  

U s i n g   I / O  

389

PART IPART I

    Console.WriteLine();

    // Now, open inventory file for reading.

    try {

      dataIn = new

          BinaryReader(new FileStream("inventory.dat",

                       FileMode.Open));

    }

    catch(IOException exc) {

      Console.WriteLine("Cannot Open Inventory File For Input");

      Console.WriteLine(exc.Message);

      return;

    }

    // Lookup item entered by user.

    Console.Write("Enter item to lookup: ");

    string what = Console.ReadLine();

    Console.WriteLine();

    try {

      for(;;) {

        // Read an inventory entry.

        item = dataIn.ReadString();

        onhand = dataIn.ReadInt32();

        cost = dataIn.ReadDouble();

        // See if the item matches the one requested.

        // If so, display information.

        if(item.CompareTo(what) == 0) {

          Console.WriteLine(onhand + " " + item + " on hand. " +

                            "Cost: {0:C} each", cost);

          Console.WriteLine("Total value of {0}: {1:C}." ,

                            item, cost * onhand);

          break;

        }

      }

    }

    catch(EndOfStreamException) {

      Console.WriteLine("Item not found.");

    }

    catch(IOException exc) {

      Console.WriteLine("Error Reading Inventory File");

      Console.WriteLine(exc.Message);

    }

    dataIn.Close();

  }

}

Here is a sample run:

Enter item to look up: Screwdrivers

18 Screwdrivers on hand. Cost: $1.50 each

Total value of Screwdrivers: $27.00.

www.freepdf-books.com

---

390

 

P a r t   I :  

T h e   C #   L a n g u a g e

In the program, notice how inventory information is stored in its binary format. Thus, the 

number of items on hand and the cost is stored using their binary format rather than their 

human-readable text-based equivalents. This makes it is possible to perform computations 

on the numeric data without having to convert it from its human-readable form.

There is one other point of interest in the inventory program. Notice how the end of the 

file is detected. Since the binary input methods throw an