1) "perl -w" in the she-bang line and "use warnings" are pretty much the same thing (won't hurt of course :-)
Here is the difference, according to warnings:
The warnings pragma is a replacement for the command line flag -w , but the pragma is limited to the enclosing block, while the flag is global. See perllexwarn for more information.

In reply to Re^2: processing key value pairs of a hash by toolic
in thread processing key value pairs of a hash by lomSpace

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