If you only want to look up exact matches, you may want to stick the lookups in a hash rather than using substitutions in a subroutine (you might use your subroutine to access the hash instead). Maybe something like this? 
my %interpret = (
    '43 F' => 'Tunnel 1/2 Hr FT',
    '43 P' => 'Tunnel 1/2 Hr PT',
    '45 F' => 'Tunnel No Lunch FT',
    '45 P' => 'Tunnel No Lunch PT',
    'F'    => 'Full Time No Clock',
    'O'    => 'On Call No Clock',
    'P'    => 'Part Time No Clock',
    'T'    => 'Temporary No Clock',
);

my $result = "43 P"; # comes from somewhere else
my $interpretation = $interpret{$result};
print $interpretation;

[download]

-- Mike

--
just,my${.02}

In reply to Re: Regex Substitution in sub by thelenm
in thread Regex Substitution in sub by peppiv

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.