Yes, once sorted, the algorithm just reads the file once in a linear fashion. So this should be great for your humongous file.

The warning message should give you a line number in the code and often you also get the line number of the input file. One common way to get an uninitialized value is when there is a blank line in the file - this causes the split to fail (no results). An extra carriage return is easy to get missed since they are "invisible". I often put: next if /^\s*$/; which will go to the next input line if the current line contains nothing but white spaces.

I think that I already mentioned that normally you probably should be splitting on the regex /\s+/ which is the default. white space (\s) includes all of the following: the space of course,\n\r\f\t any contiguous sequence of those gets removed. Splitting on just tab characters (\t) can cause problems if there are sometimes extra space characters in there that you cannot see with the editor.

I think you are on the right track - keep at it!

In reply to Re^3: Using hash keys to separate data by Marshall
in thread Using hash keys to separate data by a217

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.