Hi Irfan,
On Mon, 1 Oct 2012 01:34:51 -0700 (PDT)
Irfan Sayed <irfan_sayed2...@yahoo.com> wrote:
> hi,
>
> i need to delete all blank lines from the text file
>
How do you define a blank line? Is it an empty line? Is it a line that contains
only
whitespace?
In any case, here are a few comments on your code and after that a solution:
>
> wrote following code. however, all the blank lines are not getting
> deleted. please suggest
>
>
> open FILE,"+<", 'C:\Users\bvcontrolbuild\Desktop\test.txt';
1. Use lexical filehandles.
2. In this case the "+<" mode can be replaced by "<".
3. Use "/" instead of "\", which causes less escaping problems.
4. Throw an exception on failure - or die "Cannot open $filename - $!", or
alternatively use autodie.pm.
>
> while (<FILE>)
> {
> chomp;
> push (@lines, "$_\n");
> }
It's not a good idea to over use "$_" for loops. Use a lexical variable here.
Also, you should not chomp just to add the \n again. You can do:
my @lines = <$fh>;
> close FILE;
>
> open FILE,">", 'C:\Users\bvcontrolbuild\Desktop\test.txt';
>
> foreach (@lines)
Again, do « foreach my $l (@lines)»
> {
>
> if ($_ =~ m/^\n/)
> {
> print "hi\n";
> $_ =~ s/^\n//;
> }
> else
> {
> print FILE "$_\n";
> }
This seems fine, but it won't work if the lines contain some whitespace (and
only that).
Now for the solution. You can use https://metacpan.org/module/File::Slurp
with https://metacpan.org/module/File::Slurp#edit_file-edit_file_lines
# For removing truly empty lines.
edit_file_lines sub { s/\A\n\z//; }, 'filename';
# For removing lines containing only whitespace
edit_file_lines sub { s/\A\s+\z//; }, 'filename';
(Untested!).
Please go over this document, because you appear to keep making such mistakes:
http://perl-begin.org/tutorials/bad-elements/
Regards,
Shlomi Fish
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