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Posted by Jerry Stuckle on 11/05/64 11:41
fritz-bayer@web.de wrote:
> 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
>
I would suggest asking this in a Perl group. I'm a PHP programmer - I
know nothing about Perl.
--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================
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