You could try using a regular expression: 
#!/usr/bin/env perl
use warnings;
use strict;

check_int('55');
check_int(0xff);
check_int(123);
check_int('#123');
check_int('$123');

sub check_int {
    my $num = shift;
    if ($num =~ /\D/) {
        print "Not an integer: $num\n";
    }
    else {
        print "An integer: $num\n";
    }
}

[download]

prints out: 

An integer: 55
An integer: 255
An integer: 123
Not an integer: #123
Not an integer: $123

[download]

Can you show some examples of integers with $ and #, along with some code that you've tried?

In reply to Re: perl typecasting by toolic
in thread perl typecasting by perl_junkie

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.