swl has given a great answer that should help you understand the scope of "iterator" (for loop) variables in Perl for loops, but the real issue here is smelly code! Your sub show would be much better to take $i as a parameter so it is clear everywhere show() is used what is being shown:

for $i (1 .. 3) {
  show($1);
}

sub show {
  my ($i) = @_;
  print "$i\n";
}

[download]

That not only fixes the immediate issue, but makes the code clearer and easier to maintain.

Optimising for fewest key strokes only makes sense transmitting to Pluto or beyond

In reply to Re: Access a global variable from a subroutine when used as "for" iterator by GrandFather
in thread Access a global variable from a subroutine when used as "for" iterator by vitoco

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.