Location: [CPSC 333] [Assignments] [More about Problem to Model for Question #1 on Assignment #2]
Question:
What is a ``balance forward''?
Answer:
Think of the ``balance forward'' as the amount of money that was in the account before any of its transactions were applied, so that "opening balance" might also be a reasonable name for it.
This is also used in a way that a ``balance forward'' is used in a ``transaction register'' (or cheque book) - or (even better), in a chequing account statement that you might receive from your bank. On a chequing account statement, the ``balance forward'' is generally shown at the top of the statement, and it's the amount of money that was in the account, just before any of the transactions listed on the statement were applied. It's also either the ``opening balance'' for the account (or, maybe 0) if this is the first statement for the account you've received, or it's the ``final balance'' that was shown on the previous statement for the account, otherwise.
Now, you could use the system described in the problem statement to replace ``paper'' cheque books for several bank accounts. The problem statement describes a way to mark transactions as ``registered'' and to ``apply them,'' in order to discover what the account's balance would be if you started with the ``balance forward'' and apply only the transactions that have been ``registered'' to it. The resulting balance could be compared to the final balance shown on a bank statement, in order to check for errors in your personal records (or the bank's).
The problem statement also describes a way to delete the ``registered'' transactions, applying them in order to update the ``balance forward'' at the same time. (The problem statement calls this, having the account ``cleared''.) This is supposed to correspond to one way in which you could replace a (paper) cheque book that's been used up, with a new one: Namely, you could compute the balance you'd get by applying all the transactions that have appeared on bank statements already (namely, the ``registered'' ones), and use the result as the ``balance forward,'' or ``opening balance,'' for the new cheque book. You'd then copy all the remaining (unregistered) transactions from the old cheque book to the new one, and then use the new cheque book from then on.