Why would you want to delay writing the file? If no hash-entry exists yet, you know it can be written anyway...

Also using foreach/keys to loop thru a hash if very inefficient, especially with big hashes; perl has to traverse the entire hash to collect all the keys, and when obtaining the value in the loop body, it has to look-up the key in the hash again.

The preferred method would be to use a while/each loop. Your code would then look like:

while(my ($i,$count) = each %input) {
  print OUT "$i\n" unless $count>1;
}

[download]

Using the while/each construct would also be a lot cleaner if the hash happened to be something like a tied database query result hash, if said hash supported database row cursors... But that actually has nothing to do with the topic... :)

Happy coding, G.

In reply to Re: Re: creating a new file with unique values by Gilimanjaro
in thread creating a new file with unique values by afasch01

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.