#include <iomanip>
#include <iostream>
#include <sstream>

int main(int argc, char **argv)
{
    std::stringstream ss;
    double x = -1.890123;
    
    //insert x into the stream twice with different precisions each time
    ss << std::setprecision(2) << x << std::endl
       << std::setprecision(8) << x << std::endl;
    
    //insert the std::string representation of ss into std::cout
    std::cout << ss.str();
    
    return 0;
}