simplish script (I think)

notoriousrab430 has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I have a simple 30 line perl script which basically just compares a bunch of numbers in a list. I'm a little rusty with perl as I haven't used it in a few years now, but no matter what I try, I can't get past the syntax error which is complaining about the line where I compare two numbers out of my array. I've given up and just can't see what is wrong. Is there a monk out there who could guide me please? I hate to post up on such a simple thing, but I'm totally stuck. Running the script complains of a syntax error:

$ ./perlAnalyzeDailyStats.pl
syntax error at ./perlAnalyzeDailyStats.pl line 29, near "@array("
Execution of ./perlAnalyzeDailyStats.pl aborted due to compilation err
+ors.
[download]

  1 #!/usr/bin/perl
  2 
  3 @files = `ls -1trh s3_dailystats.*`;
  4 foreach (@files)
  5         {
  6         $filename = $_;
  7         #print $filename;
  8         open(FH,"<$filename");
  9         while(<FH>)
 10                 {
 11                 $line = $_;
 12                 if($line =~ /([0-9]{17,18})/)
 13                         {
 14                         print "$1\n";
 15                         push(@array,$1);
 16                         last;
 17                         }
 18                 }
 19         }
 20 $arrayCount = @array;
 21 print "array count is $arrayCount";
 22 foreach(@array)
 23         {
 24         if ($counter eq $arrayCount)
 25                 {
 26                 last;
 27                 }
 28         $counter++; 
 29         print "difference is " . @array($counter) - @array($counte
+r - 1);
 30         }
 31
[download]

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Re: simplish script (I think) by LanX (Saint) on Sep 25, 2020 at 00:30 UTC
Please replace all `@array($counter)` with `$array[$counter]` There are more issues but it'll help you past the syntax errors Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l] [select]
Re: simplish script (I think) by NetWallah (Canon) on Sep 25, 2020 at 00:33 UTC
An array element is referenced using SQUARE brackets and a Dollar sigil. You should be using `print "difference is " . $array[$counter] - $array[$counter - 1];` [download] Your second "foreach" is not necessary. It can be replaced by: `print "difference is " . $array[$#array] - $array[-2] , "\n";` [download] See correction below "Imaginary friends are a sign of a mental disorder if they cause distress, including antisocial behavior. Religion frequently meets that description"	[reply] [d/l] [select]
Re^2: simplish script (I think) by jeffenstein (Hermit) on Sep 25, 2020 at 08:10 UTC
Your second "foreach" is not necessary. I think the OP is trying to do this with the second foreach: `for(my $i=1; $i < @array; $i++){ print "The difference is ", $array[$i] - $array[$i-1], "\n"; }` [download]	[reply] [d/l]
Re^3: simplish script (I think) by NetWallah (Canon) on Sep 25, 2020 at 15:04 UTC
You are correct(++) - I misread the curly brackets. Another way he can achieve this - arguably more readable is: `my @a=@array; # make a copy, since we will destroy @a my $prev=pop @a; for (reverse @a){ print $prev - $_, "\n"; $prev=$_; }` [download] "Imaginary friends are a sign of a mental disorder if they cause distress, including antisocial behavior. Religion frequently meets that description"	[reply] [d/l]
Re: simplish script (I think) by jdporter (Paladin) on Sep 25, 2020 at 20:11 UTC
Sometimes I don't like using array indices. ;-) `use List::Util qw( head tail ); use List::MoreUtils qw( pairwise ); print map "difference is $_ \n", pairwise { $b - $a } @{[head(-1,@array)]}, @{[tail(-1,@array)]};` [download] relevant :-)	[reply] [d/l]
Re: simplish script (I think) by notoriousrab430 (Novice) on Sep 25, 2020 at 21:25 UTC
Thank you to those who helped me. The way of doing the if statement was better than using "last;" like I was doing. Thank you for making the internet a better place.	[reply]