Can't do it this way. The || will cast the string returned from param to a boolean. As other monks have pointed out do 
if( (length(param('tele')) > 0) ||
    (length(param('mobile')) > 0) ) {

}

[download]
However your logic doesn't match your error message - if you want to verify that the user has entered only one of the above you'll want to use && and if you want to make sure that they have entered at least one you'll want to warn when both tele and mobile are empty, i.e. length = 0 (although as pointed out before I would use defined to make sure the values aren't null).

You probably want to catch that just whitespace isn't being returned too...

In reply to Re: Checking for empty CGI params; this isn't working by stajich
in thread Checking for empty CGI params; this isn't working by andrew

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.