This code only prints the new items from file2. The main problem from Anonymous Monk's code was that it used the complete lines as hash keys...

Anonymous Monk probably needs something smarter, or more perlish, than the following snippet :
open FIRST,"file1" or die "Can't open file1: $!\n";
open LAST,"file2" or die "Can't open file2: $!\n";

my %names ;
my $write_new = 0 ;
while (<FIRST>)
{
   /(\w*) (\d*)/ ;
   $names{$1} = $2 ;
}
close FIRST;

while (<LAST>)
{
   /(\w*) (\d*)/ ;
   if (!defined($names{$1}))
   {
      $write_new++ ;
      $names{$1} = $2 ;
   }
}
close LAST;

if ($write_new)
{
    open NEW,">","file3" or die "Can't open file3: $!\n";
    foreach (sort keys %names)
    {
        print NEW "$_ $names{$_}\n" ;
    }
    close NEW;
}

[download]

Gu

Updated to avoid unnecessary opening of new file.

In reply to Re^2: file compare and populate by gu
in thread file compare and populate by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.