Commodore 1581 - The Value of Index Files

THE VALUE OF INDEX FILES
In the last two chapters you have learned how to use sequential
and relative files separately. But they are often used together, with the
sequential file used to keep brief records of which name in the relative
file is stored in each record number. That way the contents of the
sequential file can be read into a string array and sorted alphabetically.
After sorting, a technique known as a binary search can be used to
quickly find an entered name in the array, and read in or write the
associated record in the relative file. Advanced programs can maintain
two or more such index files, sorted in differing ways simultaneously.
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