#!/usr/bin/perl -wl

    use strict;
    use POSIX 'strtol';

    sub is_hex {
        local $!;
        return ! (POSIX::strtol($_[0], 16))[1];
    }


    my @hex = (0x1234, 1234, "0X1234", "beetroot", "decade", "fax");

    print is_hex($_), "\t", $_ for @hex;


    __END__
    Prints:

    1       4660
    1       1234
    1       0X1234
            beetroot
    1       decade
            fax