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

I thought setting $/ to undef would make record separated by one blank line or more.. and resulted in each record w/ separate line number

Instead I am getting number 1 and then entire information being printed.

Did I misunderstand the $/ ? or am I looping it wrong?

I was expecting a result like this

--expected results--
1hi
hi
hi

2hi
hi

3hi
hi

[download]

------------------------------------------

[root@myserver tmp]# cat perl_slurp.pl
#!/usr/bin/perl -w

use strict;

sub slurpie {
      local $/  ;
      while (<DATA>) {
           print "$. $_\n";
      }
}


slurpie();

__DATA__
hi
hi
hi

hi
hi

hi
hi
[root@myserver tmp]# ./!$
./perl_slurp.pl
1 hi
hi
hi

hi
hi

hi
hi


___________________________________________________________

[download]

*** UPDATE***

I am confused.. how does differ using $/ in inside of while loop vs outside.. local is immediate block so it should be inside of while loop?

#!/usr/bin/perl -w

use strict;

sub slurpie {
      while (<DATA>) {
           local $/  ;
           next unless /^\d+/;
           print "$. $_";
      }
}


slurpie();

__DATA__
hi
hi
234
hi

hoi
sdfsdfsdf23423
hi

hi
hi
1234

1
[root@myserver tmp]# ./!$
./././././././././perl_slurp.pl
3 234
12 1234
14 1

[download]

Replies are listed 'Best First'.
Re: $/ question
by davidrw (Prior) on Jan 13, 2008 at 02:56 UTC
    If you're undef'ing it, then you're in slurp mode, and there's no point in looping, because there's only going to be one line in the file ... 
    sub slurpie {
      local $/  ;
      return <DATA>;  # contains whole thing
}

sub DATA_w_line_numbers {
      while (<DATA>) {
           print "$.) $_";
      }
}

    [download]
    Also be sure to read through all off the perlvar section on $/ -- i think you're looking for local $/ = "";

    This may be of interest as well: Perl Idioms Explained - my $string = do { local $/; <FILEHANDLE> };
[reply]
[d/l]
[select]
      thanks, checking it out now
[reply]
        Below example do not work either.. after putting into paragraph mode
        why?
        I get --> sdfsdfsdf23423 
        #!/usr/bin/perl -w

use strict;

sub slurpie {
      while (<DATA>) {
           local $/ = "";   # put into paragraph mode (separated by one or more blank lines
           next unless /^\w\w.+(\w\w).+(\d+).+(\w\w)/sg;  #should only match first paragraph
           print "$_\n";
      }
}


slurpie();

__DATA__
hi
hi
234
hi

hoi
sdfsdfsdf23423
hi

hi
hi
1234

1
[reply]

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