A few questions

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: A few questions by btrott (Parson) on May 09, 2000 at 20:37 UTC
From perlvar, $$ is the process ID of the perl running your script. With regards to \@ and \$: I'm assuming that you're talking about something like: `my $array_ref = \@array; my $hash_ref = \%hash;` [download] Is that the case? What's happening there is that you're taking a reference to an array and a hash. References are described in perlref. They're kind of like C pointers, but also kind of not. :) References are scalars that "point" to other variables--the other variables can be arrays, hashes, scalars, etc. To use the variable pointed to by a reference, you have to dereference the reference. This could also be what you were referring to by $$, because if we had a reference to a scalar, like this: `my $string = "foo bar"; my $ref = \$string;` [download] then we could get access to the value "foo bar" by dereferencing $ref, like this: `my $original = $$ref;` [download] $original now contains "foo bar". So take a look at perlref and also at perlreftut, which might actually be a better place to start than perlref, depending on your experience.	[reply] [d/l] [select]
Re: A few questions by raflach (Pilgrim) on May 09, 2000 at 21:34 UTC
Note that $$ by itself is the process ID of your current process. Usefull in combination with other semi-random numbers for better randomization routines, and for Inter-process communication.	[reply]
Re: A few questions by zodiac (Beadle) on May 10, 2000 at 16:11 UTC
\@ is usefull if you need an array of arrays. eg: `my @x = (1, 2, 3, 4); my @y = ();` [download] and `push @y, \@x;` [download] instead of `push @y, @x;` [download] because the later will push the elements of @x onto @y, not @x itself. the same is true for \% of cause. to get the array out of the array of arrays again: `$z = pop @y; @x = @{$z}; # or @$z` [download] for more information on "strange" looking variables look at man perlvar and man perldata	[reply] [d/l] [select]