Question

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C/C++ check if one bit is set in, i.e. int variable

e.g. if I had a integer and i wanted to check what the value of bits 20-25 were, or if i just wanted to check if one of the bits is 0 or 1, how would i do that?

Answer 1

int bitsToInt(int value, int s, int e) {
    int mask = ((1 << (e - s + 1)) - 1) << s;
    return (value & mask) >> s;
}

bitsToInt(7, 2, 3) returns 1

thinking about it a bit more, if what you want is to stuff several values into one int you can be better off doing bitfields and have compiler worry about masks and shifts.