#!/usr/bin/perl -w
use strict;
$| =1; #autoflush on (sequence STDERR STDOUT timewise)

foreach my $z (1..3)
{
   my @a = map{ $_++} ('a'..'d');
   print "z=$z variable a=@a\n";
}

#prints
#z=1 variable a=a b c d
#z=2 variable a=b c d e
#z=3 variable a=c d e f

foreach my $z (1..3)
{
   #for some reason this modifies the input to the map
   #
   my @a = map{ $_++} ("a","b","c","d");
   
   #this works differently....ie, like the 2nd case in post!
   # my @a = map{my $x = $_;
   #                $x++;} ("a","b","c","d");

   print "z=$z variable a=@a\n";
}
#prints
#Modification of a read-only value attempted at 
#C:\TEMP\perl11.pl line 18.