in reply to removing comments

That would work if you ran the program like so: 

perl -i -pe 's/^\s*\'.*//' targetfilename

[download]

On the perlrun page you can see why this works (along with examples of how -p and -i expand).

You are running your substitution on the filename rather than on any of the contents of it.

-Paul

Replies are listed 'Best First'.
Re^2: removing comments
by dhudnall (Novice) on Jun 21, 2007 at 15:32 UTC
    that would work if I am running the command from the command line but I would like to be able to do it inside my program instead of having to run a command from the command line but I don't know how. Would I do something like: 
    $TheFile = $ARGV[0];
open (INFILE, $TheFile) or die
while(<INFILE>)
{




perform the removal of the comments here...or what?!? and if so what w
+ould the syntax be.

}

    [download]
    I would just like to immediately remove all comments before going any further into my massive program.
[reply]
[d/l]
      Do you want to have the entire file in memory? What do you plan to do with it, apart from removing comments? For any one line of the file, s/^'.*// will clear the comment text, leaving a blank line in its place.
      Caution: Contents may have been coded under pressure.
[reply]
[d/l]
      Your question is a bit ambigious. Do you want to
      1. create a new file with no comments
      2. load the file into memory and strip the comments before further processing
      ?

      variant 1: 
      open (my $in, "<", $ARGV[0]) 
    or die "in: $@";

open (my $out, ">", "$ARGV[0].new") 
    or die "out: $@";

while( my $line = <$in>)
{
    print $out $line
        unless $line =~ /^#/;
}

close $in;
close $out;

      [download]
      variant 2: 
      open (my $in, "<", $ARGV[0]) 
    or die "in: $@";

my @lines = grep { not /^#/ } <$in>; #<> here in list context, therefo
+re no explicit loop

      [download]
      Note that you cannot erase a line from the middle of a file, you will always have to write a new one. But you already knew that, didn't you? ;-)


      holli, /regexed monk/
[reply]
[d/l]
[select]

        Or, given the file name is in @ARGV anyway:

        $^I = '.bak';

/^#/ or print while <>;

        [download]

        to in place edit and generate a backup file.

        DWIM is Perl's answer to Gödel
[reply]
[d/l]

      You'd have to open an input and an output file — generally they're not the same one, unless you're very clever about it.

      There is actually an example on the page I linked but it may have been unobvious to locate. 

      open my $input, "<", $ARGV[0] or die "couldn't open $ARGV[0]: $!";
open my $output, ">", "output.txt" or die "coudln't open output: $!";
while(<$input>) {
    if( m/something/ ) {
        # do stuff
    }
    s/stuff//g; # etc.

    print {$output} $_;
}
close $output;
close $input;

      [download]

      -Paul

[reply]
[d/l]

In Section Seekers of Perl Wisdom