Or, as another example, try processing a file of hexadecimal numbers in POSIX standard Awk.
Another one: a few months ago I wrote an Awk function which can increment an alphanumeric string, like "A0Z" -> "A1A" -> "A1B" ...
I had to write a BEGIN block which populates global hashes for looking up the successor of a character, and whether it wraps around in its class. By character, I mean string of length 1, of course; there are no characters in Awk.
