Fastest algorithm to find the number of bits set in a number?

Hi, what is the fastest algorithm to find the number of bits set in a number?

for(count=0;number;count++)
number&=(number-1);

can anyone write a better logic for this?

For a number 'n'

c=0;

while(n)
{
c=c + (n&1);
n=n>>1;
}

This is the best algorithm as for a number 'n' the time taken is O(log n).

Create a lookup table - O(1).

hi friend..

just refer the link

[url=http://tekpool.wordpress.com/category/bit-count/]Bit Count « Technical Interview Questions[/url]

Thanks
Deepasree