Re^3: Bit fiddling madness

[BrowserUk]

built for MSWin32-x86-multi-thread-64int

The problem only(*) occurs with 32-bit perls:

C:\test>type CIDRtest.pl
#! perl -slw
use strict;
use integer;

for my $n ( 0 .. 31 ) {
    my $addr = (1 << $n) + 1;
    printf "\r%u", $addr;
    my $nbits = 32;
    while( 1 ) {
        my $bit = ( $addr & 0x80000000 ) >> 31;
        die "$addr -> $bit" if $bit != 0 and $bit != 1;
        $addr <<= 1;
        last unless --$nbits;
    }
}

C:\test>CIDRtest.pl
2147483649

C:\test>\perl32\bin\perl.exe CIDRtest.pl
-2147483648 -> -1 at CIDRtest.pl line 11.
2

(*Or 64-bit perls, but with much higher numbers.)

[mbethke]

built for MSWin32-x86-multi-thread-64int

The problem only(*) occurs with 32-bit perls:

Aaargh ... and hadn't even noticed that my laptop's system perl has 64 bit ints even though it's i686 so I'd used it for testingwhat I thought was a 32 bit system m(

Many thanks everybody, that was the whack I needed!