From: Paul Date: 2009-07-19T06:20:15+09:00 Subject: How to identify unpaired files in a list Hello there. I have a problem where I am trying to identify unpaired files in a directory. The directory may have files like the following: ---- abcd0001.txt abcd0001.def.bak abcd0002.txt abcd0003.txt abcd0003.ghi.bak abcd0004.xyz.bak ---- What I'd like to do is identify the unpaired files 'abcd0002.txt' and 'abcd0004.xyz.bak' in the list above. I've tried bringing all the filenames into a single array but I'm not sure how to delete items that have duplicate *root* names. Deleting duplicates is trivial, of course, but the extensions on the 2nd files always change. I also tried creating 2 separate arrays (one for each file type) so that I can compare the root filenames, but then I'm left with looping through one array many times.. which will have a huge performance hit when the filenames number in the 1,000's. Does anyone have any good suggestions that they can offer? Please let me know. Thanks. Paul.