Re: Replace $a with $b if $a ne $b

[Anonymous Monk]

I apologize, at the time of writing I thought it was clear. What is happening is I am looping through a list of files and I don't want to reprint the directory the files reside in for every single file. So I am trying to set $a to $b as $b changes and I am also setting $b to "" if it matches $a.

foreach $file (@filelist) {
  ($dir, $name) = split '/', $file;
  $dir =~ s/$currentdir//;
  printf("%s  %s\n", $dir, $name);
  $currentdir !~ s/$dir/$dir/;
}

so I will hopefully get output like

DIR1  FILE1
      FILE2
      FILE3
DIR2  FILE4

[Roy Johnson]

Once you've cleared $dir, it's useless to compare $currentdir to it. Maybe you want something like:

my $printed_dir = '';
foreach $file (@filelist) {
  my ($dir, $name) = split '/', $file;
  printf("%s  %s\n", ($dir eq $printed_dir ? '' : $dir), $name);
  $printed_dir = $dir;
}

[graff]

There are at least a few different (and sensible) ways to do what you want in that "foreach" loop. Personally, I'd opt for turning the list into a hash of arrays, so that it is structured in a way that is consistent with what the output should be:

my %dirhash;
for my $file ( @filelist ) {
    my ( $dir, name ) = split '/', $file;
    pushd @{$dirhash{$dir}}, $name;
}
for my $dir ( sort keys %dirhash ) {
    print "$dir\t", join( "\n\t", @{$dirhash{$dir}} ), "\n";
}

Another way, more similar to your original idea, would be to keep track of what the last printed directory was, and only print the directory name when it changes from the previous:

my $lastdir = '';
for my $file ( @filelist ) {
    my ( $dir, $name ) = split '/', $file;
    if ( $dir ne $lastdir ) {
        print "$dir";
        $lastdir = $dir;
    }
    print "\t$name\n";
}

[holli]

You shouldn't use a regex to split the filename from the path. Better take File::Basename for that.

use File::Basename;
my ($name,$path) = fileparse($fullname);