Checking if bit is not set

Question

If I use this: if(value & 4) to check if the bit is set, then how do I check if the bit isn\'t set?

I tried with if(!value & 4) or

Answer 1

When you write if(value & 4), C checks the result to be non-zero. Essentially, it means

if((value & 4) != 0) {
    ...
}

Therefore, if you would like to check that the bit is not set, compare the result for equality to zero:

if((value & 4) == 0) {
    ...
}