// checks for duplicate ISBN when attempting to update
public Boolean checkForDuplicateRecordUpdate(string enteredISBN)
{
string nextRecord;
Boolean isEndOfFile = true;
Boolean success;
int countProcessedRecords = 0;
nextRecord = currentBookFile.getNextRecord(ref isEndOfFile);
while (!isEndOfFile)
{
countProcessedRecords++;
success = book.createBookObject(nextRecord);
if (success != true)
{
MessageBox.Show
("Unable to create Book Object. Book not created.",
"Book creation failed", MessageBoxButtons.OK, MessageBoxIcon.Stop);
return(false);
} // end if statement
if (book.bookMatch(enteredISBN) == false)
{
writeOneRecord(nextRecord);
}
else
{
return(true);
}
nextRecord = currentBookFile.getNextRecord(ref isEndOfFile);
}
return(false);
}
} // end rewindFiles
// checks for duplicate ISBN when attempting to add
public Boolean checkForDuplicateRecordAdd(string enteredISBN)
{
string nextRecord;
Boolean isEndOfFile = true;
Boolean success;
int countProcessedRecords = 0;
nextRecord = currentBookFile.getNextRecord(ref isEndOfFile);
while (!isEndOfFile)
{
countProcessedRecords++;
BookClass book = new BookClass();
success = book.createBookObject(nextRecord);
if (success != true)
{
MessageBox.Show
("Unable to create Book Object. Book not created.",
"Book creation failed", MessageBoxButtons.OK, MessageBoxIcon.Stop);
} // end if statement
if (book.bookMatch(enteredISBN) == false)
{
writeOneRecord(nextRecord);
}
else
{
MessageBox.Show
("Book with ISBN: " + enteredISBN + " already exists in our library.", "ISBN error",
MessageBoxButtons.OK, MessageBoxIcon.Stop);
return(true);
}
nextRecord = currentBookFile.getNextRecord(ref isEndOfFile);
}
return(false);
}
