PERL Beginners - can not filter out commentary lines with reg-exps

Author

can not filter out commentary lines with reg-exps

Harald

2006-03-29, 7:57 am

Hi,

I need to parse an ASCII file which first rows are comments. Those rows
are marked by a '#' at their beginning.
I try to filter them out by

while( <$FH> =~ m{\#*} )
{}

But this does not work. The loop does never stop.
What goes wrong? I am really

!

Regards and thanks a lot for your help in advance,
Harald

Bjorge Solli

2006-03-29, 7:57 am

On Wednesday 29 March 2006 14:22, Harald wrote:
> I need to parse an ASCII file which first rows are comments. Those rows
> are marked by a '#' at their beginning.
> I try to filter them out by
>
> while( <$FH> =3D~ m{\#*} )

while( <$FH> =3D~ m{^\#.*} )

> {}
>
> But this does not work. The loop does never stop.
> What goes wrong? I am really

!

Your * refers to the #, saying you want to match all # occuring at least 0=
=20
times. My * refers to the . and so my regex says match a # at the beginning=
=20
of the line and the rest of that line (since * is greedy).

=2D-=20
Bj=F8rge Solli - Office:+47 55205847 cellph.:+47 91614343
Nansen Environmental and Remote Sensing Center - Bergen, Norway
http://www.nersc.no Reception: +47 55205800
Dept.: Mohn-Sverdrup Center for Global Ocean Studies=20
and Operational Oceanography

John W. Krahn

2006-03-29, 6:58 pm

Harald wrote:
> Hi,

Hello,

> I need to parse an ASCII file which first rows are comments. Those rows
> are marked by a '#' at their beginning.

You need to use '^' instead of '' to indicate the beginning of a line.

> I try to filter them out by
>
> while( <$FH> =~ m{\#*} )
> {}
>
> But this does not work. The loop does never stop.
> What goes wrong? I am really

!

Your pattern says to match zero or more of the '#' character and every line in
your file has at least zero '#' characters. You want something like:

1 while <$FH> =~ /^#/;

John
--
use Perl;
program
fulfillment

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