Sure you can. If your data is nice and normal like in the first example you can do something like this. 
@sentence = split /\s/,"perlmonk perlmonk perlmonk "; 
$numWords = @sentence;

[download]

to count the number of occurrences of perlmonk and not other words you could use the same idea but with a regular expression. I will leave it to you to figure it out. This is a clunky way to do it.... 
@sentence = split /\s/,"perlmonk perlmonk perlmonk  and some other wor
+ds that are not perlmonk"; 
foreach $word (@sentence) { 
   if ( $word =~/perlmonk/) {
      $numOccur++;
   }
}

[download]
The last one would be more tricky, but it can be done with a fairly easy regxp... something along the lines of  /p\s*e\s*..... should do the trick
Good luck.
Disclamer: all code untested and off the top of my head.

In reply to Re: count words in a line by Anonymous Monk
in thread count words in a line by benlaw

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.