What I would generally do in this case is to "start with a presumed-empty directory that has been specified by the user." Now, each time the chromosome changes, open the appropriate target file in append ">>" mode. Yes, it will be necessary for the user to be sure in-advance that the target directory is empty, but that should be fine. The program will now open each file (if it already exists) positioned at the end-of-file, or will create the file if it is new.

In reply to Re: Opening multiple output files within a loop by Anonymous Monk
in thread Opening multiple output files within a loop by TJCooper

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