my $addr = mapFile( );
substr( $addr, 32, 4 ) = pack 'V', 1+ unpack( 'V', substr $addr, 32, 4 );

##</code><code>##

$s = '0123456789';;
++substr( $s, $_, 1) for 0 .. length $s;;
print $s;;

12345678911

##</code><code>##

$s = '999999999';;
++substr( $s, $_, 1) for 0 .. length $s;;
print $s;;

11111111119999

##</code><code>##

$s = chr(0) x 40;;
vec( $s, $_, 32 ) = $_ for 0 .. 9;;
print unpack 'N*', $s;;
0 1 2 3 4 5 6 7 8 9

$s = pack 'N*', 0 .. 9;;
print vec( $s, $_, 32 ) for 0 .. 9;;
0
1
2
3
4
5
6
7
8
9

{ no warnings 'portable'; print vec( $s, $_, 64 ) for 0 .. 5 };;
1
8589934595
17179869189
25769803783
34359738377
0

##</code><code>##

++u32at( $_ ) for $start .. $end;
u64at( int rand 2**37 ) *= 3 for 1 .. 1e6;

##</code><code>##

my $totalX = u64ref( $headerSize + 3 * 8 );
...
$totalNet = $subTotalA + $subTotalB - $subTotalC;

##</code><code>##

$$totalNet = $$subTotalA + $$subTotalB - $$subTotalC;

##</code><code>##

#! perl -slw
use strict;
use warnings;

use Inline C => <<'__EOI__';

SV* f(SV* sv, I32 pos, I32 len) {
    SV* targ = newSV_type(SVt_PVLV);
    sv_magic(targ, NULL, PERL_MAGIC_substr, NULL, 0);
    LvTYPE(targ)    = 'x';
    LvTARG(targ)    = SvREFCNT_inc_simple(sv);
    LvTARGOFF(targ) = pos;
    LvTARGLEN(targ) = len;
    return targ;
}

__EOI__
use Devel::Peek qw( Dump );

sub f :lvalue;

my $x = "abcde";
my $r = ++f($x,2,1);
Dump $r;
print $x;

__END__
C:\test>ike2-lv.pl
SV = PVNV(0x3da9db8) at 0x277920
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK)
  IV = 0
  NV = 0
  PV = 0x3f044c8 "d"\0
  CUR = 1
  LEN = 8
abdde