How to get all ones or all zeros from boolean result?

I (stupidly) thought if I took the boolean result of true, cast to an int and left-shifted it I would end up with the LSB repeated at every bit, obviously not!

If I had a boolean result and I wanted to convert this to all ones for true and all zeros for false, what would be the cheapest way (computationally) to do this?

bool result = x == y;

unsigned int x = 0;

//x becomes all ones when result is true
//x becomes all zeros when result is false

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像这样，也许：

bool result = x == y;

unsigned int z = -result;

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更易读的解决方案IMO：

unsigned int set_or_unset_all_bits(bool comp) {
    return comp ? ~0u : 0;
}

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感觉如何？

int main()
{
      unsigned int x, y;
      bool b = x == y;
      x = b ? std::numeric_limits<size_t>::max() : 0;
}

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