We have recently developed a couple of utilities for Windmill Computing that are used to generate bar codes for one of their clients. This particular client is using bar code readers supplied by Telepen.
The first utility is a command-line tool used to take a list of about 1000 students, generate IDs for them, convert these IDs into bar codes and record the results in a file. This file can then be used by the software used to print the IDs cards with bar codes on them.
The second utility is a small graphical application used to generate additional IDs and bar codes on an ad hoc basis. It keeps a record of the previous ID generated to ensure each ID is unique.
The bar code is generated as a series of characters that when printed using the appropriate bar code font will produce the bar code. The sequence of characters is produced by twice adding a check digit, and employing various rules for encoding the numbers generated.