Bit manipulation tilde

Question

I understand that tilde flips every bits, but if I do int num = ~0
Why the result is num = -1 , neither max value of int or unsigned int?

http://en.wikipedia.org/wiki/Two's_complement – Jonathan Potter Oct 07 '13 at 00:08 — Jonathan Potter, Oct 07 '13 at 00:08

score 1 · Answer 1 · answered Oct 07 '13 at 00:14

1

But it is the max value of unsigned:

#include <iostream>
#include <limits>

int main() {
  std::cout << ( unsigned(-1) == std::numeric_limits<unsigned>::max() )
            << std::endl;
  return 0;
}

http://ideone.com/y4JuFe

answered Oct 07 '13 at 00:14

rici

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But if I do int unsigned int num = ~0, the result is num = 4294967295, I think this shall be the max of unsigned int – DoReMi Oct 07 '13 at 00:19
1

Unsigned 4294967295 and signed -1 have the same bit pattern. – Jonathan Potter Oct 07 '13 at 00:20

Bit manipulation tilde

1 Answers1