原创 计算学生成绩 C++

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

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

int main()
{
 // ask for and read the student's name
 cout << "Please enter your first name: ";
 string name;
 cin >> name;
 cout << "Hello, " << name << "!" << endl;
 // ask for and read the midterm and final grades
 cout << "Please enter your midterm and final exam grades: ";
 double midterm, final;
 cin >> midterm >> final;

 // ask for the homework grades
 cout << "Enter all your homework grades, "
  "followed by end-of-file: ";

 // the number and sum of grades read so far
 int count = 0;
 double sum = 0;

 // a variable into which to read
 double x;

 // invariant:
 //   we have read count grades so far, and

 //   sum is the sum of the first count grades
 while (cin >> x) {
  ++count;
  sum += x;
 }

 // write the result
 streamsize prec = cout.precision();
 cout << "Your final grade is " << setprecision(3)
   << 0.2 * midterm + 0.4 * final + 0.4 * sum / count
   << setprecision(prec) << endl;
 system("PAUSE");
 return 0;
}