If you're stuck with using scalars (I'd recommend getting unstuck ASAP and use an actual data structure) then you could do it like this 
no strict 'refs';
for($cgi->param) {
  ## &func is bad form, see. perlsub
  complain()
    unless exists  ${__PACKAGE__."::"}{$_}
       and defined *{ ${__PACKAGE__."::"}{$_} }{SCALAR}
       and defined ${ *{ ${__PACKAGE__."::"}{$_} }{SCALAR} };
}

[download]
So for each parameter check if the package variable with the name of the given parameter is defined (check symbol table entry, then type glob entry for SCALAR, then value referenced in type slot) and complain if not. So as you can see, using symbolic variables is a very icky route indeed (as Dominus illustrates very very well).
HTH

_________
broquaint

In reply to Re: Validating the contents of scalars using an array based list by broquaint
in thread Validating the contents of scalars using an array based list by JPaul

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.