Thanks for your comments, Ken. Yes, you are right, this is a 10-minutes solution, certainly not a polished one.
I needed to process the first line differently because of the way I chose to process the other lines, which would not work for the first one, but it is certainly possible to find another way to process the lines that would also work for the first one. However, when I have a header line that needs to be processed differently than the rest of the file, I often prefer to process it before starting to loop on the rest of the file, because the algorithm is then simpler (and often faster, which matters if the file is large).
You are right on the "join" line, it adds a field separator at the end of the records. That did not shock me, but it is indeed different from the output produced by the code in the original post. Adding parens (as per your proposal) solves the issue.
I had not even seen that there were two "irregular" lines with quoted fields at the beginning of the records in the input data, and that of course is a serious problem because it probably means that the whole algorithm has to be modified. BTW, this is a good example of why using a module such as Text::CSV is often better than doing one's own solution.
