I have a problem with flag bits.
I have an int
variable to hold flags. First I set some flags to that variable. Later I need check how many flags were set in that variable. But I don't know to do it.
To check to see if a bit value is set:
int value = VALUE_TO_CHECK | OTHER_VALUE_TO_CHECK;
if ((value & VALUE_TO_CHECK) == VALUE_TO_CHECK)
{
// do something--it was set
}
if ((value & OTHER_VALUE_TO_CHECK) == OTHER_VALUE_TO_CHECK)
{
// also set (if it gets in here, then it was defined in
// value, but it does not guarantee that it was set with
// OR without other values. To guarantee it's only this
// value just use == without bitwise logic)
}
It's important to note that you should not have a checked value as 0 unless it represents All or None (and don't use bitwise logic to compare; just use value == 0
) because any value & 0
is ALWAYS 0.