3-5 .cpp

Accelerted cpp 第三章答案 （部分） 一本很好的cpp入门书

#include <algorithm>
#include <iomanip>
#include <ios>
#include <iostream>
#include <string>
#include <vector>

using std::cin; 	using std::sort;
using std::cout;	using std::streamsize;
using std::endl;	using std::string;
using std::setprecision;   
using std::vector;

int main()
{
	cout << "Please enter the number of the students:";
	int number;
	cin >> number;
	
	vector<string> students;
	vector<double> grades;
	
	for(int need = 0;need != number;need++) {
	
	//ask for and read the student's name
	cout << "Please enter the student's name: ";
	string name;
	cin >> name;
	students.push_back(name);
 	cout << endl;
	
	//ask for and read the midterm and final grades
	cout << "Please enter your  midterm and final grades:";
	double midterm,final;
	cin >> midterm >> final;

	//ask for and read the homework grades
	cout << "Enter all your ten homework grades:";
	       

	vector<double> homework;
	double x;
	      //invariant: homework contains all the homework grades read so far
	for(int i = 10;i != 0;i--) {
          cin >> x;  
	      homework.push_back(x);
          }
	//check that the student entered some homework grades
	typedef vector<double>::size_type vec_sz;
	vec_sz size = homework.size(); //?
	if (size == 0) {
	    cout << endl << "You must enter your grades. "
			    "Please try again." << endl;
	    return 1; //?
	}

	//sort the grades
	sort(homework.begin(),homework.end());

	//compute the median homework grade
	vec_sz mid = size / 2;
	double median;
	median = size % 2 == 0 ? (homework[mid] + homework[mid-1]) / 2 : homework[mid];

       	//compute ane write the final grade
	double grade; 
	streamsize prec = cout.precision();
	     setprecision(3);
    grade = 0.2 * midterm + 0.4 * final + 0.4 * median ;
	     setprecision(prec);
	grades.push_back(grade);
	
	cout << endl;
	}

	return 0;
}