// 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); }