That's slick but it doesn't quite work:

    print ucwords("BATCH_USER_INFO", "_"), "\n";
    print ucwords("batch_user_info", "_"), "\n";
[download]

produces

    BATCH_USER_INFO
    batch_User_Info
[download]

In the first case you don't ever lower-case the string; in the second case you don't look for "word" at the beginning of the string, before the delim.