in reply to Re: identifying null fields in bar delimited records
in thread identifying null fields in bar delimited records

holli++

Here's a humble for loop: 

#!/usr/bin/perl

use strict;
use warnings;

my $line = "a||c|\t|  |d||e";
my @fields = split(/\|/, $line);
my @null;

for my $i (0..$#fields){
  push @null, $i unless $fields[$i];
}

print "null fields: ", scalar @null, "\n";
print "at field: ";
print ++$_, ", " for @null;

# output
# null fields: 2
# at field: 2, 7,

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Re^3: identifying null fields in bar delimited records
by lupey (Monk) on May 31, 2005 at 12:38 UTC
    holli and wfsp, great answers. Now, I'd like to make this snippet of code more general by turning the delimiter into a variable. But doing so doesn't work (I'm struggling to understand regular expressions). 
    my $delim = '|';
my $line = "a||c|\t|  |d||e";
my @fields = split(/\\$delim/, $line);

# output
# null fields: 0
# at field:

    [download]
[reply]
[d/l]
      my $delim = qr/\|/;
my $line = "a||c|\t|  |d||e";
my @fields = split($delim, $line);

      [download]

      The qr operator quotes and compiles its STRING as a regular expression.
      split splits on a pattern (regex).

      update:

      Added explanation.

[reply]
[d/l]
[select]
      I would put the escaping backslash into $delim, so you are truly independent. Besides that your code works fine and splits the string as intended. 
      my ($delim, $line, @fields);

$delim = '\|';
$line  = "a|c||b";
@fields = split(/$delim/, $line);
print join ("*", @fields), "\n";

$delim = ';';
$line  = "a;c;;b";
@fields = split(/$delim/, $line);
print join ("*", @fields), "\n";


#a*c**b
#a*c**b

      [download]
      What else did you expect?


      holli, /regexed monk/
[reply]
[d/l]
Re^3: identifying null fields in bar delimited records
by jjohhn (Scribe) on May 31, 2005 at 14:04 UTC
    I posted as anon by mistake, which means I can't edit my post to remove the superfluous line containing the variable "line".
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