Difference of & in perl and php

[fritz-bayer@web.de]

Hello,

I'm porting a program from php to perl and discovered, that the bitwise
operator & seems to work differently, which I don't understand why.

I tested it with the values:

a=5543039447 and b=13

Then in perl the expressions:

$result= ($z & $a);

returns 2147483648.

But in php the same expression returns zero. Why is that and how can I
fix it?!

Fritz

[d]

Re: Difference of & in perl and php

<fritz-bayer@web.de> wrote in message
news:1141404106 .485472.53880@z 34g2000cwc.goog legroups.com...[color=blue]
> Hello,
>
> I'm porting a program from php to perl and discovered, that the bitwise
> operator & seems to work differently, which I don't understand why.
>
> I tested it with the values:
>
> a=5543039447 and b=13
>
> Then in perl the expressions:
>
> $result= ($z & $a);
>
> returns 2147483648.
>
> But in php the same expression returns zero. Why is that and how can I
> fix it?![/color]

If you have defined $a and $b, then bitwise-anded $z and $a, you *should*
get zero, as zero AND anything is zero. If, however, you do bitwise-and $a
and $b, you shouldn't get 2147483648 in the first place, so I don't know
where your problem is :)
[color=blue]
> Fritz
>[/color]

[fritz-bayer@web.de]

Re: Difference of &amp; in perl and php


d wrote:[color=blue]
> <fritz-bayer@web.de> wrote in message
> news:1141404106 .485472.53880@z 34g2000cwc.goog legroups.com...[color=green]
> > Hello,
> >
> > I'm porting a program from php to perl and discovered, that the bitwise
> > operator & seems to work differently, which I don't understand why.
> >
> > I tested it with the values:
> >
> > a=5543039447 and b=13
> >
> > Then in perl the expressions:
> >
> > $result= ($z & $a);
> >
> > returns 2147483648.
> >
> > But in php the same expression returns zero. Why is that and how can I
> > fix it?![/color]
>
> If you have defined $a and $b, then bitwise-anded $z and $a, you *should*
> get zero, as zero AND anything is zero. If, however, you do bitwise-and $a
> and $b, you shouldn't get 2147483648 in the first place, so I don't know
> where your problem is :)
>[color=green]
> > Fritz
> >[/color][/color]

sorry, i messed up the example. I posted a follow up thread, please
forget about this one.

[Jim Michaels]

Re: Difference of &amp; in perl and php


<fritz-bayer@web.de> wrote in message
news:1141404106 .485472.53880@z 34g2000cwc.goog legroups.com...[color=blue]
> Hello,
>
> I'm porting a program from php to perl and discovered, that the bitwise
> operator & seems to work differently, which I don't understand why.
>
> I tested it with the values:
>
> a=5543039447 and b=13
>
> Then in perl the expressions:
>
> $result= ($z & $a);
>
> returns 2147483648.
>
> But in php the same expression returns zero. Why is that and how can I
> fix it?!
>
> Fritz
>[/color]

In my perl (ActivePerl 5.8.8.816 in WInXP 32-bit) I get 13 for a result.
5543039447=0x00 00 0001 4A64 11D7
it's a 33-bit number, so that may be the cause of your problem right there.
undefined behavior after the bits get too big.