Accelerated C++ 4 organizing programs and data

Student_info.h

#ifndef GUARD_Student_info #define GUARD_Student_info // Student_info.h header file #include <iostream> #include <string> #include <vector> struct Student_info{ std::string name; double midterm, final; std::vector<double> homework; }; bool compare(const Student_info&, const Student_info&); std::istream& read_hw(std::istream&, std::vector<double>&); std::istream& read(std::istream&, Student_info&); #endif

Student_info.cpp

// source file for Student_info-related functions #include <vector> #include <iostream> #include "Student_info.h" using std::cout; using std::vector; using std::istream; bool compare(const Student_info& x, const Student_info& y) { return x.name < y.name; } istream& read_hw(istream& in, vector<double>& hw) { // read and store the homework grades cout << "Enter all your homework grades, " "followd by end-of-file: "; if (in) { // get rid of previous contents hw.clear(); // read homework grades double x; while (in >> x) hw.push_back(x); // clear the stream so that input will work for the next student in.clear(); } return in; } istream& read(istream& is, Student_info& s) { // read and store the student's name and midterm and final exam grades cout << "Please enter your first name, midterm and final exam grades: "; is >> s.name >> s.midterm >> s.final; read_hw(is, s.homework); return is; }

grade.h

#ifndef GUARD_grade_h #define GUARD_grade_h // grade.h #include <vector> double median(std::vector<double>); double grade(double, double, double); double grade(double, double, const std::vector<double>&); double grade(const Student_info&); #endif

grade.cpp

// source file for the grade-ralated functons #include <vector> #include <stdexcept> #include "Student_info.h" #include "median.h" using std::vector; using std::domain_error; using std::sort; double median(vector<double> vec) { typedef vector<double>::size_type vec_sz; vec_sz size = vec.size(); if (size == 0) throw domain_error("median of an empty vector"); sort(vec.begin(), vec.end()); vec_sz mid = size / 2; return size % 2 == 0 ? (vec[mid - 1] + vec[mid]) / 2 : vec[mid]; } double grade(double midterm, double final, double homework) { return 0.2 * midterm + 0.4 * final + 0.4 * homework; } double grade(double midterm, double final, const vector<double>& hw) { if (hw.size() == 0) throw domain_error("student has done no homework"); return grade(midterm, final, median(hw)); } double grade(const Student_info& s) { return grade(s.midterm, s.final, s.homework); }

main.cpp

#include <algorithm> #include <iomanip> // setprecision #include <ios> // streamsize #include <iostream> #include <stdexcept> #include <string> #include "Student_info.h" #include "grade.h" using std::vector; using std::sort; using std::string; using std::endl; using std::domain_error; using std::cin; using std::cout; using std::max; using std::streamsize; using std::setprecision; int main(){ vector<Student_info> students; Student_info record; string::size_type maxlen = 0; // read and store all the students' data // Invariant: students contains all the student records read so far // maxlen contains the length of the longest name in students while (read(cin, record)) { // find length of longest name maxlen = max(maxlen, record.name.size()); students.push_back(record); } // alphabetize the student records sort(students.begin(), students.end(), compare); // write the names and grades for (vector<Student_info>::size_type i = 0; i != students.size(); ++i){ // write the name, padded on the right to maxlen + 1 characters cout << students[i].name << string(maxlen + 1 - students[i].name.size(), ' '); // compute and write the grade try { double final_grade = grade(students[i]); streamsize prec = cout.precision(); cout << setprecision(3) << final_grade << setprecision(prec); } catch (domain_error e) { cout << e.what(); } cout << endl; } return 0; }