Shell Programming and Scripting

Hi everybody.

I'm looking for a small function in perl to decrement a string.

For incrementing I could use the following script that is working without problem:

Code:

#!/usr/bin/perl

use strict;
use warnings;

my $string=MNO;
my $n;
print "\n start value : string\n";

for ($n=1; $n<=3; $n++){
  print "step $n:\t$string\n";
  $string++;
}

When I change the line " $string++; " to " $string--; " the shell is giving me the following result:

Code:

start value : string
step 1: MNO
step 2: -1
step 3: -2

The auto-increment operator (++) has a little extra builtin magic to it. If the variable $string has been used in only string contexts since it was set, and has a value that is not the empty string and matches the pattern /^[a-zA-Z]*[0-9]*\z/ , the increment is done as a string, preserving each character within its range, with carry.

However, as you have found out, the auto-decrement operator (--) is not magical.