There are two major changes that affected many projects, both done for security:
  1. 5.18 introduced more-randomized hashes. This shouldn't break any code, but some code only worked by chance of which order the hash keys landed normally, and will be broken now that they iterate in a different order on every run.
  2. 5.24 removed the current directory "." from the @INC include path. This breaks any project that used use MyModule; to mean require "./MyModule.pm";. You can still add the current directory back to @INC manually, but it's much better to organize the module directories and declare them all in perl -I ... or PERLLIB at startup.
Most of the rest tends to be stuff related to deprecating/removing old features from perl 4 or early versions of 5, or experimental features. If your Perl 5.16 code was written in a "normal" style, none of this should affect you.

In reply to Re: Upgrading Perl codebase of older Perl version by NERDVANA
in thread Upgrading Perl codebase of older Perl version by programmingzeal

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.