Skipping blank lines while reading a flat file.

[Dave Thacker]

Perl 5.6  on linux

Given this test file.
--start-
this

is

my file
end--
I want to skip the blank lines and just print the lines with text, like this
this
is 
myfile

This is my test case code. 
#!/usr/bin/perl -w
use strict;

my $opt_testfile=test-text.txt;
open (TS, $opt_testfile) or die can't open file;
while (TS) {
chomp;
next if ($_ =~ /^\s+/);
print $_\n;
}

I'm not skipping the lines.  My regex must be wrong.   Can someone show me my 
error please?

TIA
DT

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Re: Skipping blank lines while reading a flat file.

[Alois Heuboeck]

Dave,

(this is one I know :-) )



I want to skip the blank lines and just print the lines with text, like this
this
is 
myfile


This is my test case code. 
#!/usr/bin/perl -w

use strict;

my $opt_testfile=test-text.txt;
open (TS, $opt_testfile) or die can't open file;
while (TS) {
chomp;
next if ($_ =~ /^\s+/);


next if ($_ =~ /^\s+/);

You skip lines that BEGIN with a space.
The REGEX you want is
/^\s*$/

HTH
Alois

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Re: Skipping blank lines while reading a flat file.

[John W. Krahn]

Dave Thacker wrote:
 Perl 5.6  on linux
 
 Given this test file.
 --start-
 this
 
 is
 
 my file
 end--
 I want to skip the blank lines and just print the lines with text, like this
 this
 is 
 myfile
 
 This is my test case code. 
 #!/usr/bin/perl -w
 use strict;
 
 my $opt_testfile=test-text.txt;
 open (TS, $opt_testfile) or die can't open file;
 while (TS) {
 chomp;
 next if ($_ =~ /^\s+/);
 print $_\n;
 }
 
 I'm not skipping the lines.  My regex must be wrong.   Can someone show me my 
 error please?

Either:

next if /^\s*$/;

Or:

next unless /\S/;




John
-- 
use Perl;
program
fulfillment

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RE: Skipping blank lines while reading a flat file.

[Ron Goral]

 -Original Message-
 From: Dave Thacker [mailto:[EMAIL PROTECTED]
 Sent: Friday, October 07, 2005 07:05
 To: beginners@perl.org
 Subject: Skipping blank lines while reading a flat file.
 
 
 Perl 5.6  on linux
 
 Given this test file.
 --start-
 this
 
 is
 
 my file
 end--
 I want to skip the blank lines and just print the lines with 
 text, like this
 this
 is 
 myfile
 
 This is my test case code. 
 #!/usr/bin/perl -w
 use strict;
 
 my $opt_testfile=test-text.txt;
 open (TS, $opt_testfile) or die can't open file;
 while (TS) {
 chomp;
 next if ($_ =~ /^\s+/);
 print $_\n;
 }
 
 I'm not skipping the lines.  My regex must be wrong.   Can 
 someone show me my 
 error please?
 
 TIA
 DT

Try dropping the parens -

next if $_ =~ /^\s+/;

HTH -
Ron


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Re: Skipping blank lines while reading a flat file.

[Jeff 'japhy' Pinyan]

On Oct 7, Dave Thacker said:


Given this test file.
--start-
this

is

my file
end--
I want to skip the blank lines and just print the lines with text, like this


When you say blank, do you mean lines with NO characters at all (other 
than the ending newline) or lines that ONLY contain whitespace?



   chomp;
   next if ($_ =~ /^\s+/);


Ok, if the line is ONLY \n, then if you chomp() it, the line will be the 
empty string, .  This means it WON'T be matched by /^\s+/.


Your regex doesn't make any sense to me.  It would skip lines that start 
with a space, like  This one.  And what's the use of looking for more 
than one leading space?


I have a couple possible solutions for you.  If you want to skip lines 
that consist of ABSOLUTELY NOTHING other than a newline, then you can do:


  while (FH) {
chomp;
next if $_ eq ;
...
  }

If you want to skip lines that only have whitespace characters, then you 
can do:


  while (FH) {
chomp;
next unless /\S/;
  }

--
Jeff japhy Pinyan%  How can we ever be the sold short or
RPI Acacia Brother #734%  the cheated, we who for every service
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http://princeton.pm.org/   %-- Meister Eckhart

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