blank line in array printing

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

Hi there,
I am trying to process a small file to output some contents out of it. My input file is as below:

model_techlib \
-tech_lib_file libfile.teclib \
-device_name 12x3X1V1 -variation 0.25

output_setup \
-device_file_name 12x3X1V1DEVFILEDONOTTOUCH \
-map_file_directory_name ./


processing_setup \
-statistics_conversion_map \
A1 B1 \
CC1 DD1 \
A2 B2 \
A3 B3 \
A4 Bl4 \
A5 B5 \
A6 B6\
A56  Z56

variation_input_db \
-type signsample \
-PHI_file ../12x3X1V1.PHI   \
-PHI_LIBRARY_LIST PHI_LIB.list

sampling -type ORTHOSAMPL

results_database \
-type PHI \
-print_sigma true

print_gmm -remove_non_convergence true \
           -merge_asymptoses true
print_gmm_sigma -total_sigma_limit 1.0


solve \
-samples all \
-type PHI

#solve \
#-samples all \
#-type PHI
[download]

My Perl program to process the above file is as shown below:

#!/usr/bin/perl
use strict;
use warnings;

open(IFH,"<","testlib.tcl") || die "Cannot open input file","\n";

my $line ="";
my $cmd ="";
my @arrC = ();
while(<IFH>) {
  next if(/^#/g);
  next if(/^\n/g);
  s/^\s+//g;
  if(/\\\s*$/) {
    s/\\\s*//g;
    chomp;
    $line .= $_;
  } else {
    $line .= $_;
  }
}

#print $line;
my @arr = split(/\n/,$line);
my @test = ();
foreach (@arr) {
  if(/variation_input_db/) {
    s/variation_input_db\s*//g;
    @test = split(/-/,$_); 
  }
}

foreach (@test) {
  print $_,"\n";
}
[download]

The above file is saved as "test.pl". I executed the program as below:

neal@alnz1:~/JUNK/JUNK1$ ./test.pl
[download]

The output from the file always shows the first line as a blank line followed by the other elements of the array as below:


type signsample 
PHI_file ../12x3X1V1.PHI   
PHI_LIBRARY_LIST PHI_LIB.list
neal@alnz1:~/JUNK/JUNK1$
[download]

can some one please help why I see a blank element in my array @test ?
Thanks to you all.
Neal

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Re: blank line in array printing by ikegami (Patriarch) on Feb 23, 2009 at 03:11 UTC
I'm guessing it's related to the incorrect use of the "g" modifier in scalar context. Even if it isn't, the following is still buggy: `next if(/^#/g); next if(/^\n/g);` [download] Also, you check for empty lines, but not for lines that contains nothing but spaces. How about: `while(<IFH>) { s/#.//; if (s/\\\s$//) { $_ .= <IFH>; redo; } s/^\s+//; s/\s+$//; next if !length(); $line .= $_; }` [download]	[reply] [d/l] [select]
Re: blank line in array printing by kennethk (Abbot) on Feb 23, 2009 at 03:13 UTC
Your output begins with a blank line because the string you are splitting is `-type signsample -PHI_file ../12x3X1V1.PHI -PHI_LIBRARY_LIST PHI_LIB.list`. The string starts with a hyphen, so the first split element is a null string. As a second note, you should get in the habit of using `or` in place of `\|\|` for the phrase `or die` if you don't want to get Burned by precedence rules. Update: Prior to that split, the matching @arr element is `variation_input_db -type signsample -PHI_file ../12x3X1V1.PHI -PHI_LIBRARY_LIST PHI_LIB.list`, so perhaps you meant `s/variation_input_db\s*\-//g;`?	[reply] [d/l] [select]