There is a difference between your two loops.

for (my $i = 1; $i <= 9; $i++) {
  s/\s/;/;
}

[download]

In this loop, the variable $i goes from 1 to 9 and each time round the loop the variable $_ has a substitution applied to it.

for (1..9) {
  s/\s/;/;
}

[download]

In this loop, you don't have $i so $_ is used as the iterator variable. So when you apply the substitution to $_ you are applying it to the numbers 1 to 9.

I think that you were looking for this:

for my $i (1..9) {
  s/\s/;/;
}

[download]

which does the same thing as your first loop.

I have a nagging feeling that this may be an XY Question and that perhaps you should explain what you're really trying to do.

--

See the Copyright notice on my home node.

"The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg

In reply to Re: for loop syntax ... by davorg
in thread for loop syntax ... by cilid

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.