Re: Removing leading whitespace and removing alternate newlines
yeah, it's one of those that you shouldn't modify or you might start seeing
unexpected results. read perlvar or google 'perl input record separator' for
more.
On Mon, Nov 1, 2010 at 10:14 AM, Matthew Young wrote:
> On Oct 31, 10:01 am, brian5432...@yahoo.co.uk (Brian) wrote:
> > Hi guys, long time no working with PERL :-)
> >
> > I have just installed 5.2.12
> >
> > First, I am trying to remove leading tabs & spaces but the following
> leaves a
> > few blanks at the beginning of each line, could someone be kind enough to
> point
> > out the error of my ways please? :-)
> >
> > #!/usr/bin/perl
> >
> > local $/=undef;
> > open(FILE, "smith3.txt") || die ("Error\n");
> > $string = ;
> > $string =~ s/\s//; #remove leading spaces
> >
> > print "$string";
> >
> > Secondly, I would like to remove newline from alternate lines, ie I would
> like
> > to remove from lines 1,3,5,7 etc.
> > What would be the simplest way of getting even line numbers to print on
> the same
> > line as odds?
> >
> > Thanks muchly
> > Brian
>
> Is $/ a special variable of some kind?
>
>
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>
>
>
Re: Removing leading whitespace and removing alternate newlines
On Oct 31, 10:01 am, brian5432...@yahoo.co.uk (Brian) wrote:
> Hi guys, long time no working with PERL :-)
>
> I have just installed 5.2.12
>
> First, I am trying to remove leading tabs & spaces but the following leaves a
> few blanks at the beginning of each line, could someone be kind enough to
> point
> out the error of my ways please? :-)
>
> #!/usr/bin/perl
>
> local $/=undef;
> open(FILE, "smith3.txt") || die ("Error\n");
> $string = ;
> $string =~ s/\s//; #remove leading spaces
>
> print "$string";
>
> Secondly, I would like to remove newline from alternate lines, ie I would like
> to remove from lines 1,3,5,7 etc.
> What would be the simplest way of getting even line numbers to print on the
> same
> line as odds?
>
> Thanks muchly
> Brian
Is $/ a special variable of some kind?
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Re: Removing leading whitespace and removing alternate newlines
Thank you John
From: John W. Krahn
To: Perl Beginners
Sent: Sun, October 31, 2010 8:59:43 PM
Subject: Re: Removing leading whitespace and removing alternate newlines
Brian wrote:
> Hi guys, long time no working with PERL :-)
Hello,
> I have just installed 5.2.12
>
> First, I am trying to remove leading tabs& spaces
Just tabs and spaces? Your code says all whitespace.
> but the following leaves a
> few blanks at the beginning of each line,
You code only removes one whitespace character.
> could someone be kind enough to point
> out the error of my ways please? :-)
>
> #!/usr/bin/perl
use warnings;
use strict;
> local $/=undef;
Or just:
local $/;
> open(FILE, "smith3.txt") || die ("Error\n");
Better as:
open FILE, '<', 'smith3.txt' or die "Cannot open 'smith3.txt' $!";
> $string =;
my $string = ;
> $string =~ s/\s//; #remove leading spaces
$string =~ s/^[ \t]+//mg; #remove leading spaces and tabs from every line
> print "$string";
No need to stringify something that is alraedy a string:
print $string;
perldoc -q quoting
> Secondly, I would like to remove newline from alternate lines, ie I would like
> to remove from lines 1,3,5,7 etc.
> What would be the simplest way of getting even line numbers to print on the
>same
> line as odds?
my $count;
$string =~ s/(\n)/ $count++ % 2 ? $1 : '' /eg;
John
--
Any intelligent fool can make things bigger and
more complex... It takes a touch of genius -
and a lot of courage to move in the opposite
direction. -- Albert Einstein
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Re: Removing leading whitespace and removing alternate newlines
Brian wrote:
Hi guys, long time no working with PERL :-)
Hello,
I have just installed 5.2.12
First, I am trying to remove leading tabs& spaces
Just tabs and spaces? Your code says all whitespace.
but the following leaves a
few blanks at the beginning of each line,
You code only removes one whitespace character.
could someone be kind enough to point
out the error of my ways please? :-)
#!/usr/bin/perl
use warnings;
use strict;
local $/=undef;
Or just:
local $/;
open(FILE, "smith3.txt") || die ("Error\n");
Better as:
open FILE, '<', 'smith3.txt' or die "Cannot open 'smith3.txt' $!";
$string =;
my $string = ;
$string =~ s/\s//; #remove leading spaces
$string =~ s/^[ \t]+//mg; #remove leading spaces and tabs from every line
print "$string";
No need to stringify something that is alraedy a string:
print $string;
perldoc -q quoting
Secondly, I would like to remove newline from alternate lines, ie I would like
to remove from lines 1,3,5,7 etc.
What would be the simplest way of getting even line numbers to print on the same
line as odds?
my $count;
$string =~ s/(\n)/ $count++ % 2 ? $1 : '' /eg;
John
--
Any intelligent fool can make things bigger and
more complex... It takes a touch of genius -
and a lot of courage to move in the opposite
direction. -- Albert Einstein
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Re: Removing leading whitespace and removing alternate newlines
Thanks Shlomi, your "untested" code worked first time.
:-)
From: Shlomi Fish
To: beginners@perl.org
Cc: Brian
Sent: Sun, October 31, 2010 4:23:52 PM
Subject: Re: Removing leading whitespace and removing alternate newlines
On Sunday 31 October 2010 17:01:24 Brian wrote:
> Hi guys, long time no working with PERL :-)
>
> Secondly, I would like to remove newline from alternate lines, ie I would
> like to remove from lines 1,3,5,7 etc.
> What would be the simplest way of getting even line numbers to print on the
> same line as odds?
Use something like this (untested):
[code]
#!/usr/bin/perl
use strict;
use warnings;
my $filename = shift(@ARGV)
or die "No filename specified in command-line";
open my $fh, "<", $filename
or die "Cannot open '$filename' for reading - $!";
my $line_num = 1;
while (my $line = <$fh>)
{
chomp ($line);
$line =~ s{\A\s+}{};
print $line;
if ($line_num % 2 == 0)
{
print "\n";
}
}
continue
{
$line_num++;
}
close($fh);
[/code]
Regards,
Shlomi Fish
>
> Thanks muchly
> Brian
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Re: Removing leading whitespace and removing alternate newlines
Thank you Shlomi, I'll test part 2 tomorrow when I have more time.
As for part one, what would be the better way of writing the code so that I can
read/treat one line at a time?
thanks again
Brian
From: Shlomi Fish
To: beginners@perl.org
Cc: Brian
Sent: Sun, October 31, 2010 4:23:52 PM
Subject: Re: Removing leading whitespace and removing alternate newlines
On Sunday 31 October 2010 17:01:24 Brian wrote:
> Hi guys, long time no working with PERL :-)
>
> I have just installed 5.2.12
>
You probably mean perl-5.12.2 .
A few more comments on your code:
> First, I am trying to remove leading tabs & spaces but the following leaves
> a few blanks at the beginning of each line, could someone be kind enough
> to point out the error of my ways please? :-)
>
> #!/usr/bin/perl
>
> local $/=undef;
You probably don't want to read the entire file to memory at once, as it may
be very large.
> open(FILE, "smith3.txt") || die ("Error\n");
Use three-args-open, lexical filehandles, and use a more descriptive error
than "Error.".
> $string = ;
> $string =~ s/\s//; #remove leading spaces
>
This will remove only the first whitespace character (and in your case, from
the entire file).
> print "$string";
>
>
>
> Secondly, I would like to remove newline from alternate lines, ie I would
> like to remove from lines 1,3,5,7 etc.
> What would be the simplest way of getting even line numbers to print on the
> same line as odds?
Use something like this (untested):
[code]
#!/usr/bin/perl
use strict;
use warnings;
my $filename = shift(@ARGV)
or die "No filename specified in command-line";
open my $fh, "<", $filename
or die "Cannot open '$filename' for reading - $!";
my $line_num = 1;
while (my $line = <$fh>)
{
chomp ($line);
$line =~ s{\A\s+}{};
print $line;
if ($line_num % 2 == 0)
{
print "\n";
}
}
continue
{
$line_num++;
}
close($fh);
[/code]
Regards,
Shlomi Fish
>
> Thanks muchly
> Brian
--
Re: Removing leading whitespace and removing alternate newlines
On Sunday 31 October 2010 17:01:24 Brian wrote:
> Hi guys, long time no working with PERL :-)
>
See:
http://perl.org.il/misc.html#pl_vs_pl
> I have just installed 5.2.12
>
You probably mean perl-5.12.2 .
A few more comments on your code:
> First, I am trying to remove leading tabs & spaces but the following leaves
> a few blanks at the beginning of each line, could someone be kind enough
> to point out the error of my ways please? :-)
>
> #!/usr/bin/perl
>
Add strict and warnings. See:
http://perl-begin.org/tutorials/bad-elements/
> local $/=undef;
You probably don't want to read the entire file to memory at once, as it may
be very large.
> open(FILE, "smith3.txt") || die ("Error\n");
Use three-args-open, lexical filehandles, and use a more descriptive error
than "Error.".
> $string = ;
> $string =~ s/\s//; #remove leading spaces
>
This will remove only the first whitespace character (and in your case, from
the entire file).
> print "$string";
>
>
>
> Secondly, I would like to remove newline from alternate lines, ie I would
> like to remove from lines 1,3,5,7 etc.
> What would be the simplest way of getting even line numbers to print on the
> same line as odds?
Use something like this (untested):
[code]
#!/usr/bin/perl
use strict;
use warnings;
my $filename = shift(@ARGV)
or die "No filename specified in command-line";
open my $fh, "<", $filename
or die "Cannot open '$filename' for reading - $!";
my $line_num = 1;
while (my $line = <$fh>)
{
chomp ($line);
$line =~ s{\A\s+}{};
print $line;
if ($line_num % 2 == 0)
{
print "\n";
}
}
continue
{
$line_num++;
}
close($fh);
[/code]
Regards,
Shlomi Fish
>
> Thanks muchly
> Brian
--
-
Shlomi Fish http://www.shlomifish.org/
Best Introductory Programming Language - http://shlom.in/intro-lang
She's a hot chick. But she smokes.
She can smoke as long as she's smokin'.
Please reply to list if it's a mailing list post - http://shlom.in/reply .
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Re: Removing leading whitespace and removing alternate newlines
$string =~ s/^\s+//;
http://oreilly.com/catalog/9781565922433/ page 43
That book is my bible!!!
On Sun, Oct 31, 2010 at 11:01 AM, Brian wrote:
> Hi guys, long time no working with PERL :-)
>
> I have just installed 5.2.12
>
> First, I am trying to remove leading tabs & spaces but the following leaves
> a
> few blanks at the beginning of each line, could someone be kind enough to
> point
> out the error of my ways please? :-)
>
> #!/usr/bin/perl
>
> local $/=undef;
> open(FILE, "smith3.txt") || die ("Error\n");
> $string = ;
> $string =~ s/\s//; #remove leading spaces
>
> print "$string";
>
>
>
> Secondly, I would like to remove newline from alternate lines, ie I would
> like
> to remove from lines 1,3,5,7 etc.
> What would be the simplest way of getting even line numbers to print on the
> same
> line as odds?
>
> Thanks muchly
> Brian
>
>
>
--
Richard Hug
813-973-3783
cell 813-361-7946
Removing leading whitespace and removing alternate newlines
Hi guys, long time no working with PERL :-)
I have just installed 5.2.12
First, I am trying to remove leading tabs & spaces but the following leaves a
few blanks at the beginning of each line, could someone be kind enough to point
out the error of my ways please? :-)
#!/usr/bin/perl
local $/=undef;
open(FILE, "smith3.txt") || die ("Error\n");
$string = ;
$string =~ s/\s//; #remove leading spaces
print "$string";
Secondly, I would like to remove newline from alternate lines, ie I would like
to remove from lines 1,3,5,7 etc.
What would be the simplest way of getting even line numbers to print on the
same
line as odds?
Thanks muchly
Brian
