From: Logan Capaldo <logancapaldo@...>
Date: 2005-12-10T04:15:59+09:00
Subject: Re: new to Ruby - pls help in translating this


On Dec 9, 2005, at 1:48 PM, Sam Dela Cruz wrote:

> Hi,
>
> I'm starting to use Ruby in one of my projects at work.  I'm coming  
> from a
> Perl background.
> In my project I would need to parse a list of numbers (thousands of  
> them)
> and then return the duplicates.  In perl, I can do this:
>
> ##### Perl code
> %hash = {};
> while (<>)
> {
>     chomp;
>         $hash{$_}++;
> }
>
> foreach my $key (sort keys %hash)
> {
>     print "$key: $hash{$key}\n" if ($hash{$key} > 1);
> }
>

hash = Hash.new { |h, k| h[k] = 0 }

while gets
     $_.chomp!
     hash[$_] += 1
end

> I tried to translate this in Ruby, but could not find en equivalent of
> $hash{$_}++, this is auto increment.

Ruby has no auto-increment since variables are more like labels on  
objects than containers for objects and numbers are generally  
immutable in ruby.
IOW:
x = 3
x++ in ruby would be like typing 3++ which doesn't make sense really.

> Can somebody tell me how this is to be done in Ruby?  Or maybe the  
> Ruby
> way on how to attack this whole thing.  Thanks.
>
> Regards,
> Sam