Loop by bit shift

[sroberts82]

Hi
I want to do a for loop by bit shift, so I loop through 0,1,2,4,8 etc... 0,1,10,100,1000 etc
So I did this:

for(int i =0x1; i<100; i = i<<1)
{
//do stuff
}

Thats fine, but it leaves out zero. I can't start at zero cos a bit shift on zero is zero. I was thinking if I cut off the least significant bit of i I would get what I want...but I don't know how to do that. Can someone help?
Thanks

 

[Salem]

What is wrong with handling case 0 outside the loop, then all other cases with the loop?


--
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.

 

[cpjust]

You could put this at the end of the loop:

if ( i == 0 )
{
   i = 1;
}

 

[xwb]

Are you allowed to do it backwards?

ii = 0x10000; // Must be 1 bit more than required
do {
   ii >>= 1;
   ...
} while (ii != 0);

That will do 0x8000 through to 0.

 

[lionelhill]

Or you could do exactly as you said: loop from 1 upwards, and make use of that value shifted one place to the right inside the loop.