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Posted by fritz-bayer@web.de on 11/03/07 11:41
Jerry Stuckle wrote:
> d wrote:
> > "Jerry Stuckle" <jstucklex@attglobal.net> wrote in message
> > news:6vCdnYaBloS7MZXZnZ2dnUVZ_vidnZ2d@comcast.com...
> >
> >>d wrote:
> >>
> >>>"Jerry Stuckle" <jstucklex@attglobal.net> wrote in message
> >>>news:P4qdnZ1ghuZKFJXZRVn-qw@comcast.com...
> >>>
> >>>
> >>>>fritz-bayer@web.de wrote:
> >>>>
> >>>>
> >>>>>Hi,
> >>>>>
> >>>>>why does the php expression
> >>>>>
> >>>>>$result = 5543039447 & 2147483648;
> >>>>>
> >>>>>when executed evaluate to 0, whereas the perl expression
> >>>>>
> >>>>>$same = 5543039447 & 2147483648 ;
> >>>>>
> >>>>>evaluate to 2147483648 ???
> >>>>>
> >>>>>Fritz
> >>>>>
> >>>>
> >>>>Because Perl is using 64 bit integers and PHP is using 32 bit integers.
> >>>>
> >>>>2147483648 is not a valid value in 32 bit arithmetic. The largest value
> >>>>you can have is 2147483647.
> >>>
> >>>
> >>>PHP interprets ints over 32 bits as floats, so they are valid.
> >>>
> >>>"If you specify a number beyond the bounds of the integer type, it will
> >>>be interpreted as a float instead. Also, if you perform an operation that
> >>>results in a number beyond the bounds of the integer type, a float will
> >>>be returned instead."
> >>>
> >>>
> >>>
> >>>>--
> >>>>==================
> >>>>Remove the "x" from my email address
> >>>>Jerry Stuckle
> >>>>JDS Computer Training Corp.
> >>>>jstucklex@attglobal.net
> >>>>==================
> >>>
> >>>
> >>>
> >>In most cases, yes. However, you cannot perform bit operations on a
> >>float. It must be an integer type.
> >>
> >>So the value is converted back to an integer, and since it's outside the
> >>bounds of a 32 bit integer the result is to strip off the high order bits.
> >>
> >>The result is zero.
> >
> >
> > The result is zero regardless of whether that bit is there or not :)
> >
> >
> >>Sometimes a little knowledge is worse than no knowledge at all.
> >>
> >
> >
> > Indeed.
> >
> >
> >>--
> >>==================
> >>Remove the "x" from my email address
> >>Jerry Stuckle
> >>JDS Computer Training Corp.
> >>jstucklex@attglobal.net
> >>==================
> >
> >
> >
>
> Actually, 0x80000000 is -2147483647 decimal. So the result is not zero.
>
> --
> ==================
> Remove the "x" from my email address
> Jerry Stuckle
> JDS Computer Training Corp.
> jstucklex@attglobal.net
> ==================
How can I port the php code, which return 0 (zero), and looks exactly
like this:
<?php
$a = 5543039447;
$b = 2147483648;
$result = ($a & $b);
echo "$result\n" ;
?>
to perl? In perl almost the exactly same code:
#!/usr/bin/perl
$a = 5543039447;
$b = 2147483648;
$result = ($a & $b);
print "$result\n" ;
returns 2147483648.
How do I have to modify the perl code, so that it will actually do a
bitwise and? I don't get - any workaround? Somethings I'm not getting
here? I'm using linux debian/sarge with an intel 32 bit prozessor.
Fritz
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