C++: File Processing: matching sequential files

Question

I have a small problem. I have three files, OldMaster, Transaction and NewMaster. If the account numbers match between OldMaster and Transaction, I update the balance and write it to NewMaster. If they don't match, I write the original account info from OldMaster to NewMaster and display an error.

There are 4 accounts in file OldMaster and 4 account transactions in file Transactions. For some reason my program is not processing the fourth (last) account/transaction in each file and NewMaster is not receiving data.

int accountNumber
int accountNum;
string lastName;
string firstName;
float currentBalance;
float dollarAmount;

inOldMaster >> accountNumber >> firstName >> lastName >> currentBalance;
inTransaction >> accountNum >> dollarAmount;

while ( !inOldMaster.eof() && !inTransaction.eof() )
{
    if ( accountNumber == accountNum )
    {
        currentBalance += dollarAmount;
        outNewMaster << accountNum << " " << firstName << " " << lastName << " " 
                     << currentBalance << endl;
    } 
    else if (accountNumber != accountNum)
    {
        outNewMaster << accountNumber << " " << firstName << " " << lastName << " " 
            << currentBalance << endl;
        cout << "Unmatched transaction record for account number: " << accountNum 
            << endl;
    }

    inOldMaster >> accountNumber >> firstName >> lastName >> currentBalance;
    inTransaction >> accountNum >> dollarAmount;
}

Answer 1

When you read the data from the input files, if end-of-file is reached in the loop, the loop will not continue and so not write out the newly read data.

If your case I would do something like this:

do
{
    inOldMaster >> accountNumber >> firstName >> lastName >> currentBalance;
    inTransaction >> accountNum >> dollarAmount;

    if (inOldMaster.bad() || inTransaction.bad())
        break;

    // Your old if-statements

} while (inOldMaster.good() && inTransaction.good());