#!/usr/bin/perl
     # check for numbers with punctuation

     use Strict;

     # examples for "common-written" numbers 
     foreach my $var (

             # should be false
             '','foo 30','.20','20.',',20','20,',    

             # should be numbers
         0,100,'100.23','1,100.23' 
         
                      ) {

             if (IsANumber($var)) {
                     print "True:    $var\n";
             } else {
                     print "False:   $var\n";
             }

     }

             
     sub IsANumber {

             my $var = $_[0];
             
             if (

               # contains digits,commas and 1 period
               ($var =~ /(^[0-9]{1,}?$)|(\,*?)|(\.{1})/) &&

               # does not contain alpha's, more than 1 period
               # commas or periods at the beggining and ends of
               # each line
               !($var =~ /([a-zA-Z])|(^[\.\,]|[\.\,]$)/) &&

               # is not null
               ($var ne '')

               ) { return(1) } 
               else { return(0) }
     }