> You could also say for (0..$a_big_number) { ... }, but that is no way to save memory.

Actually, it is. For some time now that style of foreach loop has been optimized. It doesn't create a list of $a_big_number+1 elements; it efficiently iterates one at a time through the set, much as the equivalent C-style for loop would.

You can prove this to yourself by using a really big number and watching the memory of the program as it runs (say, through top): 

foreach (0..100_000_000) { $i++ }

[download]

Compare this with the memory usage of something like the following. Notice I had to drop the number from 100 million to just one million; 100 million caused perl to die with an out of memory error. 

@array = (0..1_000_000);
foreach (@array) { $i++ }

[download]

This optimization was added to perl 5.005; perldoc perl5005delta mentions it, search for 1000000.

In reply to Re: Re: Two Questions on "my" by Somni
in thread Two Questions on "my" by C_T

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.