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Perl Script Hangs on Empty File

Posted on 2010-09-24
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Last Modified: 2012-05-10
I have the attached perl script which formats a file. However if the file is empty, the perl script hangs. Can you please edit the script so it exits if the file is empty?
PostProcess.txt
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Question by:copiacap
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5 Comments
 
LVL 16

Expert Comment

by:Justin Mathews
ID: 33754457
my $input = $ARGV[0] || die "Please specify input file\n";
open(INPUT, $input) || die "Can't open input file $input: $!\n";
1 while( ($_=<INPUT>) !~ /^name\s+number\s+symbol\s+initial/ && /./);
do {
   chomp;
   my @F = split/\t/;
   print join("\t",@F[0..14])."\n";
} while( <INPUT> );
close(INPUT);
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Accepted Solution

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Justin Mathews earned 2000 total points
ID: 33754603
My previous solution will exit if it finds a blank line. To exit with error if the input file is empty use the following:

my $input = $ARGV[0] || die "Please specify input file\n";
-s $input || die "Empty input file\n";
open(INPUT, $input) || die "Can't open input file $input: $!\n";
1 while( ($_=<INPUT>) !~ /^name\s+number\s+symbol\s+initial/);
do{
   chomp;
   my @F = split/\t/;
   print join("\t",@F[0..14])."\n";
} while( <INPUT> );
close(INPUT);
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LVL 85

Expert Comment

by:ozo
ID: 33759855
my $input = $ARGV[0] || die "Please specify input file\n";
open(INPUT, $input) || die "Can't open input file $input: $!\n";
while( <INPUT> ){
  next unless /^name\s+number\s+symbol\s+initial/..0;
   chomp;
   my @F = split/\t/;
   print join("\t",@F[0..14])."\n";
}
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LVL 85

Expert Comment

by:ozo
ID: 33768592
that still hangs on a non-empty file that does not contain name\s+number\s+symbol\s+initial
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LVL 16

Expert Comment

by:Justin Mathews
ID: 33770893
Sorry, try this:

my $input = $ARGV[0] || die "Please specify input file\n";
-s $input || die "Empty input file\n";
open(INPUT, $input) || die "Can't open input file $input: $!\n";

while ($_=<INPUT>) {/^name\s+number\s+symbol\s+initial/ && last}

do{
   chomp;
   my @F = split/\t/;
   print join("\t",@F[0..14])."\n";
} while( <INPUT> );
close(INPUT);
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