Your iterator function has a few problems with it.

First, the code does not give the output you suggest. To make your code work properly, the while condition should read:

while (($_) = $iter->()) {

[download]

The () around $_ is necessary as $iter->() returns () when the iterator is done.

Second, the code does not allow foreach()-like behaviour. $_ is not aliased to the array element value and does not allow expressions such as the following to have effect: (from the original node)

$_ = uc $_;

Third, the range operator ('..') still creates a list that is 1000000 scalars long, and copies this list into the array. Try the following code, and watch your machine quickly die:

$ perl -e 'push(@a, [1 .. 1000000]) while 1'

(NOTE: The range operator optimization only applies when used directly from a foreach loop. For example: 'for (1 .. 1000000) { ... }')

All in all, a for(;;) loop with a 'local *_ = \ $array[$i]' is far more effective and efficient... :-)

In reply to Re: Re: Starting foreach at an arbitrary position by MarkM
in thread Starting foreach at an arbitrary position 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.