How To Determine Installed Modules
August 27, 2003
Here’s how to determine what modules have been installed after the original Perl installation, hence showing those modules not part of the core installation. Type this from a command line:
perldoc perllocal
How To Tell A Number From A String
August 13, 2003
Often, I need to compare two variables but I don’t know if they are numbers or strings. I need to know the type so I can pick the proper comparison operators, i.e., == or eq, > or gt.
So, here’s how to do it:
~$x ne ~"$x" ? 'numeric' : 'string'
~ is the bitwise negation operator (see perlop). It does not negate integers and strings in the same way.
Examples:
$ perl -e 'print ~1, "\n"' 4294967294 $ perl -e 'print ~"1", "\n"' Œ
(character which ASCII code is 255 - ord(’1′))