Re: Sorting Unique File Entries

This is a very simple pure Perl solution that will work also on Win32 machines; it is based on an associative array in order to kill duplicate entries. What's nice with it is that if you add to the printing loop $hDat{$d} you get to know how many times a line was repeated.

use strict;
my %hDat;
my $d;

map( $hDat{$_}++, <DATA> );

foreach $d (sort keys %hDat) { print $d; }

__DATA__
a
b
c
dd
c
aa
zzzz
q
r
[download]

You could also use a similar approach to perform a case-insensitive duplicate line removal that returns the last instance of the duplicate line in the full majesty of its original case:

use strict;
my %hDat;
my $d;

map( ($hDat{lc $_} = $_), <DATA> );

foreach $d (sort keys %hDat) { 
    print $hDat{$d}; 
}

__DATA__
a
Bongo
c
BoNgo
dd
c
A
zzzz
q
r
[download]

Comment on Re: Sorting Unique File Entries Select or Download Code

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Re: Re: Sorting Unique File Entries by l3nz (Friar) on Nov 24, 2003 at 17:42 UTC
This is a somehow shorter version using the same technique but no named temporary array (it's more an exercise in concision than actually useful). `use strict; foreach my $d (sort keys %{{ map( ($_ => 1), <DATA>) }} ) { print $d; } __DATA__ a B a B dd` [download] I wonder if there's a cleaner way to write the `map`ped expression.	[reply] [d/l] [select]