How do I check, if bitmask contains bit?

Question

I don't quite understand this whole bitmask concept.

Let's say I have a mask:

var bitMask = 8 | 524288; 

I undestand that this is how I would combine 8 and 524288, and get 524296.

BUT, how do I go the other way? How do I check my bitmask, to see if it contains 8 and/or 524288?

To make it a bit more complex, let's say the bitmask I have is 18358536 and I need to check if 8 and 524288 are in that bitmask. How on earth would I do that?

Answer 1

well

if (8 & bitmask == 8 ) { } 

will check if the bitmask contains 8.

more complex

int mask = 8 | 12345; if (mask & bitmask == mask) {    //true if, and only if, bitmask contains 8 | 12345 }  if (mask & bitmask != 0) {    //true if bitmask contains 8 or 12345 or (8 | 12345) } 

may be interested by enum and more particularly FlagsAttibute.

Answer 2

I'm pretty sure (A & B)==B where A is the bitmask and B is whatever you want to check should do.

Example:

if((18358536 & 8) == 8)  {     // mask contains 8 }