The following line of code is from Stein's "Official Guide to Programming with CGI.pm", (page 73). 
grep ($fields{$_}++, @fields);

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I understand what the code is doing (ie: setting the keys for the hash %fields equal to the elements in the array @fields). What I don't understand is why it works. What is the autoincrement doing? Can anyone explain this?

Thanks.

In reply to Use of grep with arrays/hashes by Anonymous Monk

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