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From: Lew <noone@lewscanon.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: Java left shift and right shift operators.
Date: Tue, 26 Apr 2011 11:24:31 -0400
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Travers Naran wrote:
> Sanny wrote:
>>> Is there any way to avoid the if condition and do right shift and left
>>> shift using operators depending on shiftby is +ve or -ve?
>>
>> I used below technique but it gives error.
>>
>> divider=Math.pow(2,shiftby);

Please follow Java naming conventions.

>> then
>> output = (long) N / divider;

> My advice:
> if (shift>0) output = N >> shiftby; else output = N << (-shiftby);
>
> The above is pretty efficient, and once the hotspot compiler gets a hold of
> it, it will be even faster.
>
> There is no assembly operator that shifts based on +/- bits; there are only
> shift-left and shift-right operators. If there was a Java operator/function to
> do what you want, it would still be implemented (in machine language) as:

Doesn't matter, the Java operator *is* defined for negative values.

So the solution to Sanny's problem is:

  output = n >> shiftBy;

-- 
Lew
Honi soit qui mal y pense.
http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg