# [LinuxBIOS] Another dumb C question

Joseph Smith joe at smittys.pointclark.net
Thu Jul 12 14:34:24 CEST 2007

```Quoting Joseph Smith <joe at smittys.pointclark.net>:

> Quoting Corey Osgood <corey.osgood at gmail.com>:
>
>> Joseph Smith wrote:
>>> Quoting Peter Stuge <peter at stuge.se>:
>>>
>>>
>>>>> value = 9
>>>>>
>>>>> (2 << (value - 1))
>>>>>
>>>>>
>>>
>>>
>>>> Bit shift is fine methinks but I would suggest:
>>>>
>>>> (1 << value)
>>>>
>>>>
>>>> (2 << (value - 1))
>>>>
>>>>
>>>> //Peter
>>>>
>>>>
>>> Not sure I understand. I am trying to get 2 "to the power of" value.
>>>
>>> if value = 9
>>> (1 << value)
>>> This equals 18???? Not 2^9 = 512
>>> where
>>> (2 << (value - 1))
>>> (2 << (9 - 1))
>>> 2 << 8 = 512
>>>
>>> Thanks - Joe
>>>
>>>
>> remember that 2 = (1 << 1). so 2 << (value - 1) = 1 << value. I'm not
>> sure where you're getting an 18 from, that makes no sense at all (since
>> 18 in either hex or dec has two non-zero bits, so it's impossible to get
>> that result with just that binary shift).
>>
>> -Corey
>>
>>
> Well lets see if value = 9, which is 1001 in binary.
> If you bitshift 1001 one position to the left it becomes 10010, correct?
> Which is 18 in decimal.
>
> Thanks - Joe
>
Nevermind I get it. I was looking at it bass ackwards :-)
Sorry, I'm a little tired.

Thanks - Joe

```