#!/usr/bin/perl

use strict;
use warnings;

my ($num, $let, $foo);
$num = "z";
$let = $num;
# $foo = 1 + $num;  # this does not modify $num
$num++; $let++;
print "num:$num let:$let\n";

__END__

##</code><code>##

num:aa let:aa

##</code><code>##

Argument "z" isn't numeric in addition (+) at C:\temp\foo.pl line 9.

##</code><code>##

C:\temp>perl -le "$a='z';print++$a"
aa

C:\temp>perl -le "$a='9';print++$a"
10

##</code><code>##

C:\temp>perl -MO=Concise -e "$a='z'" >z
-e syntax OK

C:\temp>cat z
6  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
5     <2> sassign vKS/2 ->6
3        <$> const[PV "z"] s ->4
-        <1> ex-rv2sv sKRM*/1 ->5
4           <#> gvsv[*a] s ->5

C:\temp>perl -MO=Concise -e "$a='9'" >9
-e syntax OK

C:\temp>diff z 9
5c5
< 3        <$> const[PV "z"] s ->4
---
> 3        <$> const[PV "9"] s ->4

##</code><code>##

C:\temp>perl -le "$a='foo9';print++$a"
fop0

C:\temp>perl -le "$a='9bar';print++$a"
10