CIS 150 C++ Programming Project: Random access (binary) file I/O

Objectives

• Create a loop with a menu of options
• Write to a binary file
• Read from a binary file
• Use a struct to store a record's data
• Format output

Overview

This assignment involves the use of a struct and a random access binary file. You will create the user interface which lets the user store and retrieve records. Each record in the file has the following fields:

• id: integer
• price: double
• quantity: integer

Requirements

Implement the following pseudocode:

Define a struct that matches the description of the record above.

main:
    Declare any needed local variables.
    Create a variable to store one record.

    // The complicated logic in this section takes care of the 
    // case when the file does not initially exist.
    open the file "rafile.bin" for binary input and output
    if it did not open then
        // File did not exist so create it
        open the file "rafile.bin" for binary output
        if the file opened then
            // File exists now, so reopen for input and output
            close the file
            open the file "rafile.bin" for binary input and output
        otherwise
            // File still does not exist, so end the program
            display an error message (file could not be opened)
            exit with an error status
    
    find out how many records are in the file and store that in numRecs
    display the number of records that are in the file
    
    do the following
        display a menu as shown in the sample runs provided with this assignment
        get the user's choice and convert it to lowercase
        if the user chose to read a record then
            ask for a record number
            if that record number does not exist then
                display an error message
            otherwise
                read that record and display it (with 2 decimals for price)
        otherwise if the user chose to append a record then
            get an id, price, and quantity from the user and store it in a record
            write that record to the end of the file
            increase the numRecs variable
            display which record number was written to the file
        otherwise if the user chose to quit then
            do nothing
        otherwise
            display an error message for invalid option chosen
    while the user has not chosen to quit

    close the file
    exit with a success status

Sample Run

There are 0 records in the file
r) read a record
a) append a record
q) quit
Enter your choice: d
Invalid choice. Try again.
r) read a record
a) append a record
q) quit
Enter your choice: r
Record number to read: 0
Error: Invalid record number.
r) read a record
a) append a record
q) quit
Enter your choice: r
Record number to read: 1
Error: Invalid record number.
r) read a record
a) append a record
q) quit
Enter your choice: a
Enter an ID: 33
Enter a price: 13.1
Enter a quantity: 2
Record 1 written to file
r) read a record
a) append a record
q) quit
Enter your choice: 7778
Invalid choice. Try again.
r) read a record
a) append a record
q) quit
Enter your choice: Invalid choice. Try again.
r) read a record
a) append a record
q) quit
Enter your choice: Invalid choice. Try again.
r) read a record
a) append a record
q) quit
Enter your choice: Invalid choice. Try again.
r) read a record
a) append a record
q) quit
Enter your choice: a
Enter an ID: 7778
Enter a price: 45.626
Enter a quantity: 1
Record 2 written to file
r) read a record
a) append a record
q) quit
Enter your choice: r
Record number to read: 1
33: $13.10 (2)
r) read a record
a) append a record
q) quit
Enter your choice: r
Record number to read: 2
7778: $45.63 (1)
r) read a record
a) append a record
q) quit
Enter your choice: q

Rubric

1. Note: Points may be deducted for not meeting the course coding standards.
2. 2 points for having the struct correct
3. 3 points for getting the file opened properly for reading and writing binary data
4. 3 points for correctly figuring out the number of records
5. 3 points for having a correct input loop that quits when it should
6. 1 points for converting the user menu choice to lowercase
7. 2 points for having a correctly functioning menu so each choice does the proper thing
8. 6 points for getting the read menu option functioning properly
9. 2 points for formatting the output of a record read as shown in the sample run
10. 8 points for getting the append menu option functioning properly