use strict;
use warnings;

#use vars ('$M','$N');
 
#  local $SIG{__WARN__} = sub { $N=24 };
  
  my $t_num = sub { $N=24 };
  printf "\nThe value of N is now %s %d %o\n",$N,$N,$N;

  $M = sprintf "%x", 41;
  printf "\nThe value of M is now %s %d %o\n",$M,$M,$M;

  my $t_var = sub { 
     $M = 42;
     # printf "\nThe value of M is now %s %d %o\n",$M,$M,$M;
     sub { $M };
  };
  
  printf "\nThe value of t_var is now %s %d %o\n",$t_var->(),$t_var->(),$t_var->();
  printf "\nThe value of M is now %s %d %o\n",$M,$M,$M;

=head1 output

Global symbol "$N" requires explicit package name at v42_13.pl line 10.
Global symbol "$N" requires explicit package name at v42_13.pl line 11.
...
Global symbol "$M" requires explicit package name at v42_13.pl line 23.
Global symbol "$M" requires explicit package name at v42_13.pl line 23.
Execution of v42_13.pl aborted due to compilation errors.

=cut

=head uncommented 'use vars ('$M','$N');' output

Use of uninitialized value $N in printf at v42_13.pl line 11.
Use of uninitialized value $N in printf at v42_13.pl line 11.
Use of uninitialized value $N in printf at v42_13.pl line 11.
The value of N is now  0 0
The value of M is now 29 29 35
The value of t_var is now CODE(0xxxxxxxxxx) dddddddd ddddddddddd
The value of M is now 42 42 52

=cut