Lab 6 -- CheckSums
Thursday, May 16, 2002
- To practice parsing with get
A local bank has instituted a new credit system and would like to
have account numbers that are self-checking in order to have
some protection against fraud and clerical errors. They
have devised the following system: the account numbers will be nine
digits long where the last digit can be calculated by finding
the sum of the first eight digits and taking the rightmost digit
of the sum. For example, if the account number was 333333334, the
sum of the first eight digits is 24. 4 is the rightmost digit of 24
equals the ninth digit of the account number. Therefore, the account is
valid. The ninth digit of the account is called a checksum.
Your job is to complete a program that can be used to check the validity
of account numbers.
First, you should download the starter code and
input file from blackduck.
In the "esc014pub" directory is a directory named "lab 6".
Transfer this directory to the DesktopAnnex folder on your desktop.
Go back to lab 1 if you need a refresher
on the instructions.
Inside the "lab 6" folder is an input file of account numbers
named "accounts.txt". Each account number is on a separate
line. The last line is a semicolon that you can use as
a sentinel to determine when the input file ends.
There is also starter code named "yourNameHere.cpp".
Change the filename to your own
name (keep the .cpp extension). You should NOT alter this code.
Besides the main function, two auxiliary functions have already
been written for you. The first, called validChecksum,
returns true if the given checksum character is equal to
the last digit of the given sum. It returns false otherwise. In
the example above, giving validChecksum the checksum
character '4' and the sum of 24 as parameters would return true.
The other function given to you is digitToNumber. It
converts the given char to its equivalent representation as an int.
It's the same function given to you on p. 357 of your text.
The function you will write is named processData.
It takes no parameters. This function will read in
the account numbers character-by-character using the get
command. As it reads in the characters, it will compute
the sum of the first 8 digits, read in the checksum (ninth) digit,
and then call validChecksum to determine if the account
number is valid or not. It should then inform the user if
the account number is valid or not. Your output will look something
333333334 is a valid account number.
111111110 is an invalid account number.
Make sure to process the input yourself by hand to
check the validity of your test results.
How to turn in this lab
Remember, you will be graded on the correctness
of your implementation, neatness, presentation, style of your program
thoroughness of your testing, and good use of the C++ language. It's
to comment your code where appropriate and to do little things like
properly, use readable indentation, and also to make sure the overall
logic of the program are coherent.
Turn in a hard copy of your source code along with your test
results appended at the
bottom as a comment. Then turn in the source code electronically on
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