I'm doing something where I'll be inserting things into arbitrary places in an array based on a priority, and I need to keep the array sorted. Finding the place to put the new item is no problem, but I need to shift everything in the array over to make room for the insertion. This works: 
$idx = 45; # pretend we've already found the insertion point
@a[$idx+1 .. $#a+1] = @a[$idx .. $#a];
$a[$idx] = $newitem;

[download]
But I have vague notions of blatant inefficiency, especially for large lists. I'm worried more about speed than memory use, but I don't know how this would compare to just explicitly moving one element at a time. Is it best just to do the old: 
$idxmove = $#a;
while ($idxmove >= $idx) {
  $a[$idxmove+1] = $a[$idxmove];
  $idxmove--;
}
$a[$idx] = $newitem;

[download]

In reply to Shifting an Array by kelan

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.