C - C++ (string question)

#include <iomanip>#include <iostream>#include <sstream>#include <boost/format.hpp>int main(){	{ // using manipulators		float total = 3.71f;		std::ostringstream sstr;		sstr << "The total is $" << std::setiosflags(std::ios::fixed) << std::setprecision(2) << total;		std::string string = sstr.str();		std::cout << string << '\n';	}	{ // using stringstream member functions		float total = 3.71f;		std::ostringstream sstr;		sstr.flags(std::ios::fixed);		sstr.precision(2);		sstr << "The total is $" << total;		std::string string = sstr.str();		std::cout << string << '\n';	}	{ // alternative - using boost::format		float total = 3.71f;		boost::format format("The total is $%.2f");		std::string string = (format % total).str();		std::cout << string << '\n';	}}