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Hi,
I must parse files of this form:

field1,,,field4,,field6,,,,,,


That is, the fields of each line are separated by a comma, and the fields
can be empty.

With awk I can do this:

awk -F, '{print $6; print NF}'

with the above line I get:
field6
12
and that's what I want


How can I get the same result with Perl?
I tried:

perl -F, 'print $F[5];print $#F+1'

which gives:
field6
5

Perl drops the "empty" fields after the last non-empty field

On 2006-09-24, Awkish <> wrote:
> Perl drops the "empty" fields after the last non-empty field

=> perl -e 'use Data:umper; my $q = q{field1,,,field4,,field6,,,,,,}; my @w = split /,/, $q, -1; print Dumper(\@w);'
$VAR1 = [
'field1',
'',
'',
'field4',
'',
'field6',
'',
'',
'',
'',
'',
''
];

depesz

--
mój bo¿e, spraw abym milcza³, dopóki siê nie upewniê, ¿e naprawdê mam
co¶ do powiedzenia. (c) 1998 depesz

Awkish wrote:
> Hi,
> I must parse files of this form:
>
> field1,,,field4,,field6,,,,,,
>
>
> That is, the fields of each line are separated by a comma, and the fields
> can be empty.
>
> With awk I can do this:
>
> awk -F, '{print $6; print NF}'
>
> with the above line I get:
> field6
> 12
> and that's what I want
>
>
> How can I get the same result with Perl?
> I tried:
>
> perl -F, 'print $F[5];print $#F+1'
>
> which gives:
> field6
> 5
>
> Perl drops the "empty" fields after the last non-empty field

Yes, this is a feature of the default beaviour of split() but can be
overidden by making the 3rd argument negative.

AFAIK there's no way to do this with autosplit so you need to spell it
out.

perl -ne '@F=split/,/,$_,-1; print $F[5];print $#F+1'

Brian McCauley wrote:
> perl -ne '@F=split/,/,$_,-1; print $F[5];print $#F+1'

Oops, forgot the chomp! There probably should be a chomp too.

perl -nle '@F=split/,/,$_,-1; print $F[5];print $#F+1'

Mumia W. (reading news) wrote:
> #!/bin/sh
>
> echo 'field1,,,field4,,field6,,,,,,' | \
> perl -wle '
> while (<>) {
> @F = split /,/, $_;
> print $F[5];
> print scalar @F;
> }
> '

You forgot to chomp(). (That's what made me realise I'd done so too in
another branch).

That'll be OK if $F[5] is not the last element but if any line in the
input has exactly 6 fields then you'll get an extra newline in the
output.

If you'd not forgotten to chomp() then you would have gotten away with
omitting the -1 on the split().

Note: If you use the -n switch with the -l switch Perl will insert the
chomp for you.

perl -wnle '
@F = split /,/, $_, -1;
print $F[5];
print scalar @F;
'

Brian McCauley wrote:

> If you'd not forgotten to chomp() then you would have gotten away with
> omitting the -1 on the split().

That should, of course, say "wouldn't have gotten away".

Awkish wrote:
....

> With awk I can do this:
>
> awk -F, '{print $6; print NF}'
>
> with the above line I get:
> field6
> 12
> and that's what I want
>
>
> How can I get the same result with Perl?
....

perldoc a2p

--
Bob Walton
Email: http://bwalton.com/cgi-bin/emailbob.pl

On Sun, 24 Sep 2006 12:18:11 +0200, Awkish <> wrote:

>Hi,
>I must parse files of this form:
>
>field1,,,field4,,field6,,,,,,
>
>
>That is, the fields of each line are separated by a comma, and the fields
>can be empty.
>
>With awk I can do this:
>
>awk -F, '{print $6; print NF}'
>
>with the above line I get:
>field6
>12
>and that's what I want
>
>
>How can I get the same result with Perl?
>I tried:
>
>perl -F, 'print $F[5];print $#F+1'

According to the description in perlrun (ahem), you need

perl -an -F, "print $F[5],$#F+1"

I tried it. It works.
--
Eric Amick
Columbia, MD

Eric Amick wrote:
> On Sun, 24 Sep 2006 12:18:11 +0200, Awkish <> wrote:
>
>>I must parse files of this form:
>>
>>field1,,,field4,,field6,,,,,,
>>
>>That is, the fields of each line are separated by a comma, and the fields
>>can be empty.
>>
>>With awk I can do this:
>>
>>awk -F, '{print $6; print NF}'
>>
>>with the above line I get:
>>field6
>>12
>>and that's what I want
>>
>>How can I get the same result with Perl?
>>I tried:
>>
>>perl -F, 'print $F[5];print $#F+1'
>
> According to the description in perlrun (ahem), you need
>
> perl -an -F, "print $F[5],$#F+1"
>
> I tried it.

Are you really, really, *really* sure that you tried it?


> It works.

Prove it.



John
--
use Perl;
program
fulfillment

Hi thanks for all your insights, you're very helpful.