Re: How to delete the line I have just read?

Hi,

If I am not wrong then follow this code

my $filename = 'yourfilename.txt';
open FILE, "$filename" || die "cant open file for read";

@data = <FILE>;

close FILE;

for my $line (0..$#data) {

    # execute process method -- do your operation stuffs here.
    
    &process($data[$line]);

    # if you want to delete, make the line with null value;

    $data[$line] = "";

}



$entirefile = join "\n", @data;

open OUT, "outfile.txt" || die "cant open file for write";

print OUT $entirefile;

close OUT;
[download]

Comment on Re: How to delete the line I have just read? Download Code

Replies are listed 'Best First'.
Re^2: How to delete the line I have just read? by chromatic (Archbishop) on Aug 04, 2008 at 19:40 UTC
That code could be prettier, but it has a serious bug in it: `# if you want to delete, make the line with null value; $data[$line] = "";` [download] This doesn't actually delete the line; it replaces it with an empty line. Oh, and there's another bug -- why join lines on newlines when you haven't chomped away existing newlines? Here's much better code: `my $filename = 'yourfilename.txt'; my $newfile = 'new_filename.txt'; filter_file( $filename, $newfile ); # this line may be unnecessary depending on your filesystem unlink $filename; rename( $filename, $newfile ); sub filter_file { my ($from, $to) = @_; open my $fh, $from or die "Can't read '$from': $!\n"; open my $out_fh, '>', $to or die "Can't write '$to': $!\n"; while (<$fh>) { next if should_delete_line($_); print {$out_fh}; } }` [download]	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^2: How to delete the line I have just read?
by chromatic (Archbishop) on Aug 04, 2008 at 19:40 UTC

That code could be prettier, but it has a serious bug in it:

    # if you want to delete, make the line with null value;

    $data[$line] = "";
[download]

This doesn't actually delete the line; it replaces it with an empty line. Oh, and there's another bug -- why join lines on newlines when you haven't chomped away existing newlines? Here's much better code:

my $filename = 'yourfilename.txt';
my $newfile  = 'new_filename.txt';

filter_file( $filename, $newfile );

# this line may be unnecessary depending on your filesystem
unlink $filename;
rename( $filename, $newfile );

sub filter_file
{
    my ($from, $to) = @_;
    open my $fh,          $from or die "Can't read '$from': $!\n";
    open my $out_fh, '>', $to   or die "Can't write '$to': $!\n";

    while (<$fh>)
    {
        next if should_delete_line($_);
        print {$out_fh};
    }
}
[download]

[reply]
[d/l]
[select]