Hi again,

I'm very sorry: the mail was out and I found an error in the program
(corrected version attached).

This perhaps answers my unsureness about '.':

$ printf ".\na\0b\n" | ./test_regex 
Compiling regex "."
Testing string "610062"...
regexec match: pos 0 length 1
        "a"
Testing string "0062"...
regexec match: pos 2 length 1
        "b"

But this expression matches '\0':

$ printf "[^\\\x01-\\\xff]\na\0b\n" | ./test_regex 
Compiling regex "[^\x01-\xff]"
Testing string "610062"...
regexec match: pos 0 length 1
        "a"
Testing string "0062"...
regexec match: pos 1 length 1
        ""
Testing string "62"...
regexec match: pos 2 length 1
        "b"

Regards,

Dirk