My Proposed Design

• Main
     Open Files
     while there is data
        read in next data
        process next data
     print final report
  

• There is a problem with this.
  • It is designed with the end of file bug.
• Revision

• Main
     Open Files
     Read in next data
     while there is data
        process next data
        Read in next data
     print final report
      

• As a side comment, I will turn this into the code

  int main() {
  
      string productName;
      float priceA, priceB;
      int quantity;
      bool valid;
      float totalCost = 0;
      float totalSave = 0;
  
      ifstream fileA, fileB;
  
      OpenFiles(fileA, fileB);
      GetData(fileA, fileB, productName, priceA, priceB, quantity, valid);
      while (valid) {
          ProcessData(productName, priceA, priceB, quantity, totalCost, totalSave);
          GetData(fileA, fileB, productName, priceA, priceB, quantity, valid);
      }
      CloseFiles(fileA, fileB);
      FinnalReport(quantity, valid);
  
      return 0
  } 

  • In any case, this is way premature.
  • I just wanted to show how I will eventually turn a high level design into code.
• An early structure chart might be
• Let's focus on OpenFiles
  • What does this need to do?
  • Open the configuration file
  • Then open the other two files.
  • Do we know enough to implement this?
  • What is the input to this function? (or what do we need to pass to it)
  • What is the output of this function? (or what will it return)

  • OpenFiles
       Input: None
       Output: Two file streams
               a bool that indicates if the file streams are valid or not.
    
    Get file names
    Open first file 
    Open the second file
    Set the flag to indicate that the files are valid.  

  • In this case, I decided to go one level deeper at least for get file names.
  • I have some confusion on how this will be done, so I want to isolate it so it is easy to change.
  • Notice a common routine, OpenAFile.
• 
• GetFileNames
  • This again has no input
  • But it will return two strings, the file names.
  • I still don't know how to get the configuration file name.
  • I also don't know what to do in case of error.
  • How do I resolve these questions?

  • set valid to false
    repeat
        Prompt for file name
        attempt to open file
    until a file is open
    read in the first data file name
    read in the second data file name
    if both file names were read in successfully
         set valid to true
    close the configuration file 

  • This seems concrete.
  • It seems coheasive.
• Open a file
  • Input: the file name
  • Output:
    • a file stream
    • A flag indicating if the file was successfully opened.

  • set flag to false
    open the file
    if the file was opend successfully
       set the flag to true 

  • This might be too simple for a routine, but it will make readable code.
• GetData
  • This will take the two open file streams.
  • And return
    • The product name
    • The first price
    • The second price
    • The quantity
    • A flag to indicate success

  • Set valid to false
    Get data from the first file
    Get data from the second file
    If both are successful
       set valid to true
             

  • I don't know how I am going to deal with the input so I will delay that.
• Or take it up. GetDataFromFile1
  • The line is in the form Name Of Item| price quantity
  • The problem is arbitrary spaces
    • In the name
    • Between the other items.
  • I don't know how to handle this right now
  • But I still need to do the design so
  • Input: the file handle
  • Output:
    • The item name
    • The first price of the item
    • The quantity of the item.
    • A flag indicating if the read was successful

  • set success to false
    Get the item name
    Get the item price
    Get the item quantity
    if successful 
       set success to true
            

  • I really want to make a note that I am not sure how to do this.
• GetDataFromFile2 is similar.
• Process Data
  • Input
    • Product name
    • cost 1
    • cost 2
    • Quantity
    • Item number (I missed this above)
  • Output
    • Updated savings
    • Updated total cost.

  • Compute price difference
    Compute Savings
    Add savings to total savings
    Compute total cost
    Add cost to total cost
    Print data line
             

  • Of these, I think the last one is abstract, everything else is concrete.
• PrintFinalReport
  • Input: TotalSavings and Total Cost.
  • No need to write this algorithm.
• In the end, the structure chart is: