iOS a question about operator

[joonbear]

Hi all, I don't know below operator (&) mean.
Could you help to explain that.
Thanks a lot.

NSUInteger width = 3;
if((width != 1) && (width & (width - 1)))
{
}

 

[robbieduncan]

Same as it means in C: bitwise and.

 

[ianray]

Same as it means in C: bitwise and.

And, as such, this code is checking whether 'width' is not a power of 2.

if((width != 1) && (width & (width - 1)))

Code for checking is-a-power-of-2 is commonly a test of the form:

x && !(x & (x-1))