ulong bitwise shift

[Francois St-Arnaud]

Hello All,

I have the following property in a C# class in a .NET 2003 project:

public const ulong MASK_1 = 0x8000000000000 000;

I find the following observations unsettling (from my Command Window -
Immediate):

MASK_1
0x8000000000000 000
MASK_1 >> 1
0x4000000000000 000
MASK_1 >> 2
0x2000000000000 000
MASK_1 >> 3
0x1000000000000 000
MASK_1 >> 4
0x8000000000000 00
MASK_1 >> 5
0x4000000000000 00

What? A wraparound on the 4 MSBs? I'm I missing something?

Francois.

[Peter Koen]

Re: ulong bitwise shift

"Francois St-Arnaud" <Sfrancois.star naudP@Avideotro n.caM> wrote in
news:q4Pnb.9257 $zB4.37753@wagn er.videotron.ne t:
[color=blue]
> MASK_1
> 0x8000000000000 000
> MASK_1 >> 1
> 0x4000000000000 000
> MASK_1 >> 2
> 0x2000000000000 000
> MASK_1 >> 3
> 0x1000000000000 000
> MASK_1 >> 4
> 0x8000000000000 00
> MASK_1 >> 5
> 0x4000000000000 00
>
> What? A wraparound on the 4 MSBs? I'm I missing something?
>[/color]

Please, count the zeroes. Your code is just missing to print out leading
0's.

Better do something like this:

Console.WriteLi ne("0x{0:X16}" , MASK);

--
------ooo---OOO---ooo------

Peter Koen - www.kema.at
MCAD CAI/RS CASE/RS IAT

------ooo---OOO---ooo------

[Jon Skeet [C# MVP]]

Re: ulong bitwise shift

Francois St-Arnaud <Sfrancois.star naudP@Avideotro n.caM> wrote:[color=blue]
> I have the following property in a C# class in a .NET 2003 project:
>
> public const ulong MASK_1 = 0x8000000000000 000;
>
> I find the following observations unsettling (from my Command Window -
> Immediate):
>
> MASK_1
> 0x8000000000000 000
> MASK_1 >> 1
> 0x4000000000000 000
> MASK_1 >> 2
> 0x2000000000000 000
> MASK_1 >> 3
> 0x1000000000000 000
> MASK_1 >> 4
> 0x8000000000000 00
> MASK_1 >> 5
> 0x4000000000000 00
>
> What? A wraparound on the 4 MSBs? I'm I missing something?[/color]

That looks fine to me - note that there are fewer 0s at the end of the
versions which are shifted right by 4 or 5 bits than there are for the
other ones. If you shift to a decimal display rather than hex it will
be more obvious.

--
Jon Skeet - <skeet@pobox.co m>

http://www.pobox.com/~skeet

If replying to the group, please do not mail me too

[Francois St-Arnaud]

Re: ulong bitwise shift

AH! Thanks! I'm going blind!
I think that I got confused because I had the same code in a C++ project in
another .NET window, but the tooltip popups and the Watch window showed the
leading zeroes; not so in a C# project.

"Jon Skeet [C# MVP]" <skeet@pobox.co m> wrote in message
news:MPG.1a09d0 dcfc90ef6798998 4@msnews.micros oft.com...[color=blue]
> Francois St-Arnaud <Sfrancois.star naudP@Avideotro n.caM> wrote:[color=green]
> > I have the following property in a C# class in a .NET 2003 project:
> >
> > public const ulong MASK_1 = 0x8000000000000 000;
> >
> > I find the following observations unsettling (from my Command Window -
> > Immediate):
> >
> > MASK_1
> > 0x8000000000000 000
> > MASK_1 >> 1
> > 0x4000000000000 000
> > MASK_1 >> 2
> > 0x2000000000000 000
> > MASK_1 >> 3
> > 0x1000000000000 000
> > MASK_1 >> 4
> > 0x8000000000000 00
> > MASK_1 >> 5
> > 0x4000000000000 00
> >
> > What? A wraparound on the 4 MSBs? I'm I missing something?[/color]
>
> That looks fine to me - note that there are fewer 0s at the end of the
> versions which are shifted right by 4 or 5 bits than there are for the
> other ones. If you shift to a decimal display rather than hex it will
> be more obvious.
>
> --
> Jon Skeet - <skeet@pobox.co m>
> http://www.pobox.com/~skeet
> If replying to the group, please do not mail me too[/color]