Re: testing if just one bit is set...

On Nov 6, 1:42 pm, ".rhavin grobert" <cl...@yahoo.de> wrote:


an int is not necessarily 32 bits. That depends on the platform.
bitset has a member function count() which returns a count of bits
set.
Use that. If thats too slow for you, try release mode instead of
debug.

#include <iostream>
#include <bitset>

template< typename T >
bool checkbits(const std::bitset< sizeof(T) * 8 >& r)
{
  return (r.count() > 1) ? true : false;
}

int main ()
{
  int n(257);
  std::bitset< sizeof(int) * 8 > b(n);

  for (std::size_t i = b.size(); i > 0; --i)
  {
    std::cout << b.test(i - 1);
    if((i-1)%4 == 0)
      std::cout << " ";
  }
  std::cout << std::endl;

  if(checkbits< int >(b))
    std::cout << "more than one bit set\n";
  else
    std::cout << "less than 2 bits set\n";
}

/*
0000 0000 0000 0000 0000 0001 0000 0000
result: less than 2 bits set
*/