C++ How to Program, 10/e

14.6 Updating Sequential Files

Data that is formatted and written to a sequential file as shown in Section 14.3 cannot be modified without the risk of destroying other data in the file. For example, if the name “White” needs to be changed to “Worthington,” the old name cannot be overwritten without corrupting the file. The record for White was written to the file as

300 White 0.00

If this record were rewritten beginning at the same location in the file using the longer name, the record would be

300 Worthington 0.00

The new record contains six more characters than the original record. Therefore, the characters beyond the “h” in “Worthington” would overwrite the 0.00 and the beginning of the next sequential record in the file. The problem ...