On Sat, May 30, 2009 at 23:32, Raabe, Wesley <wra...@kent.edu> wrote:
>
> I am using regular expressions to alter a text file. Where my original file
> has three spaces to start a paragraph, I want to replace each instance of
> three spaces with a bracketed paragraph number, with a counter for paragraph
> numbers, <pgf 1>, <pgf 2>, <pgf 3> etc. The PERL program that I'm using is
> modeled on the answer to chapter 9, question 3 in the Learning Perl book (4th
> ed.).
>
> The WHILE loop that I've crafted is like this:
>
> while (<IN>) {
> chomp;
> s/\ \ \ /\<pgf\ (?{my $para_num = 1; $para_num++;){print
> "$para_num";}})\>/gi; # Replace three spaces with <pgf XX>
> print OUT "$_\n";
> }
>
> I'm trying to embed the PERL code based on the PERL tutorial
> (http://perldoc.perl.org/perlretut.html#A-bit-of-magic%3a-executing-Perl-code-in-a-regular-expression>,
> which is noted as an experimental feature. But it doesn't work (using MAC
> OSX). The output in my text file is "<pgf (?{my = 1; ++;){print "";}})" at
> start of each paragraph.
>
> Is there a way to do this with AUTO-INCREMENT variable and a FOR loop outside
> the regular expression in which the value is inserted inside the regular
> expression? My earlier attempts to do it that way always resulted in no
> change in the value, just <pgf 1> on every paragraph time.
snip
That would be because the second part of a s/// is not a regex, it is
a double quote string. What you want is the /e option which
interprets the second part as Perl code instead:
my $i = 0;
while (<IN>) {
s/[ ]{3}/"<pgf " . $i++ . ">"/ge;
print;
}
--
Chas. Owens
wonkden.net
The most important skill a programmer can have is the ability to read.
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