Accelerated C++ 3 working with batches of data

s.percision(n) 

Sets the precision of stream s to n for future output (or leaves it unchanged if n is omitted). Returns the previous precision.

setprecision(n)

Returns a value that, when written on an output stream s, has the effect of calling s.precidion(n). Defined in <iomanip>

#include <algorithm>#include <iomanip>#include <ios>#include <iostream>#include <string>#include <vector>int main() {    // ask for and read student's name    std::cout << "Please enter your first name: " ;    std::string name;    std::cin >> name;    std::cout << "Hello, " << name << "!" << std::endl;    // ask for and read the midterm and final grades    std::cout << "Please enter your midterm and final exam grades: ";    double midterm, final;    std::cin >> midterm >> final;    // ask for and read the homework grades    std::cout << "Enter all your homework grades, "                    "followed by end-of-file: ";    std::vector<double> homework;    double x;    // invariant: homework contains all the homework grades     while(std::cin >> x) {        homework.push_back(x);    }    // check that the student entered some homework grades    typedef std::vector<double>::size_type vec_sz;    vec_sz size = homework.size();    if (size == 0 ) {        std::cout << "You must enter your grades. "                         "Please try again." << std::endl;        return 1;    }    // sort the grades    std::sort(homework.begin(), homework.end());    // compute the median homework grade    vec_sz mid = size / 2;    double median;    median = size % 2 ? homework[mid] : (homework[mid - 1] + homework[mid]) / 2;    // compute and write the final grade    std::streamsize prec = std::cout.precision();    std::cout << "Your final grade is " << std::setprecision(3)                 << 0.2 * midterm + 0.4 * final + 0.4 * median                << std::setprecision(prec) << std::endl;    return 0;}