Define a large bitset in C++

Question

In my program I need to check if I have already generated a value in a set of 2.5*10^9. I expect to generate about the half of the set and need to have a fast way to check a

Answer 1

Use std::vector instead of std::bitset for large sizes.

Answer 2

This may not be your problem, but try to allocate the bitset on the heap with new, instead of using the stack.

Some systems limit the size of the stack, which might be what causes problems for you.

Answer 3

I think the following solution is better than using new

    std::vector<std::bitset<2500000000UL>> wrapper(1);
    auto & cover = wrapper[0];//To avoide unnecessary indirection by wrapper[0]

To demonstrate

int main(){
    std::vector<std::bitset<2500000000UL>> wrapper(1);
    auto & cover = wrapper[0];
    cover[0] = 1;
    std::cout << cover[0] << " " << cover[2500000000UL - 1];
}