Convert bool array to int32 ,unsigned int and double?

Question

I\'ve bool arrays of sizes : 32, 48, 64 (each boolean represents a bit). how can I convert them to a number with a good performance( int, unsigned int, double48, double64)?

Answer 1

#include 
#include 
#include 

enum class endianness : bool { big, little };

constexpr endianness getEndianness()
{
    uint32_t word = 1;
    uint8_t* byte = (uint8_t*)& word;

    if(byte[0])
        return endianness::little;
    else
        return endianness::big;
}

constexpr bool isLittleEndian()
{
    switch(getEndianness())
    {
        case endianness::little:
            return true;
        case endianness::big:
            return false;
    }
}

auto make_bitSet (bool flags[], size_t size)
{
    std::bitset< 8*sizeof(ULLONG_MAX) > bitSet;

    if( isLittleEndian() )
        for (size_t i = 0; i < size; ++i)
            bitSet.set( i, flags[size-i-1] );
    else
        for (size_t i = 0; i < size; ++i)
            bitSet.set( i, flags[i] );

    return bitSet.to_ullong();
}

int main (int, char**)
{
    bool ar1[] = {1, 0, 1, 0            };
    bool ar2[] = {1, 0, 1, 0, 1, 1, 0, 0};
    bool ar3[] = {1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0};
    bool ar4[] = {1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0};
    bool ar5[] = {1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0,
                  1, 0, 1, 0, 1, 1, 0, 0};

    std::cout << make_bitSet(ar1,  4) << '\n';
    std::cout << make_bitSet(ar2,  8) << '\n';
    std::cout << make_bitSet(ar3, 16) << '\n';
    std::cout << make_bitSet(ar4, 48) << '\n';
    std::cout << make_bitSet(ar5, 64) << std::endl;

    return 0;
}

cout

10
172
44204
189857631349932
12442509728149187756