Bitwise Operators

// Test data.
List<uint> nums = new List<uint>();
nums.Add(Convert.ToUInt32("10100010", 2));
nums.Add(Convert.ToUInt32("00101001", 2));
nums.Add(Convert.ToUInt32("10101000", 2));
nums.Add(Convert.ToUInt32("00100001", 2));
nums.Add(Convert.ToUInt32("10000101", 2));


// Target minimum.
int minMatches = 4;


// Variables.
bool success = false;
int count;
int lastBit = (int)Math.Log(Int32.MaxValue, 2);


// Loop through each bit position.
for (int i = 0; i <= lastBit; i++)
{

    // Count the number of bits that are set at the current position.
    count = 0;
    for (int j = 0; j < nums.Count; j++)
    {
        if (((((uint)1) << i) & nums[j]) != 0)
        {
            count++;
        }
    }


    // If the minimum number of matches was found, we're done here.
    if (count >= minMatches)
    {
        success = true;
        break;
    }

}


// Success!
if (success)
{
    string msg = "There were at least {0} numbers that had at least one common set bit.";
    MessageBox.Show(string.Format(msg, minMatches.ToString()));
}

// Requires VC2010 C++0x additions

#include <array>
#include <bitset>
#include <algorithm>
#include <iostream>

int main()
{
    typedef std::bitset<8> Val;

    // The test data
    static std::array<Val, 5> vals =
    {
        Val("10100010"),
        Val("00101001"),
        Val("10100010"),
        Val("00100001"),
        Val("10000101")
    };

    // A lambda to sum the bit values at position nPos in vals elements
    auto SumBits = [&](size_t nPos) -> size_t {
        size_t n = 0;
        std::for_each(vals.cbegin(), vals.cend(), [&](const Val& val){n += val.test(nPos);});
        return n; };

    const size_t wanted = 4;
	
    for (auto i = 0; i < Val::_EEN_BITS; ++i) // check each bit position
    {
	auto sum = SumBits(i);
	if (sum >= wanted) // if found report and exit
	{
		std::cout << sum << " bits set at position " << i << std::endl;
		return i;
	}
    }

    std::cout << "No position with "<< wanted << " bits set" << std::endl;
    return 0;
}