binary to double

#include <iostream>

using namespace std;

int main()
{
    string str = "011111111001001010100000000000000000000000000000000000000000000";
    long long a = stol(str, nullptr, 0);
    long long *b = (long long *)malloc(sizeof(long long));
    *b = a;
    cout << *(double *)b << endl;
    return 0;
}