Accelerated 13 Using inheritance and dynamic binding

Core.h

#ifndef GUARD_core_h#define GUARD_core_h// Core.h#include <string>#include <iostream>#include <vector>class Core {    public:        Core():midterm(0),final(0) { }        Core(std::istream& is) { read(is); }        std::string name() const;        virtual std::istream& read(std::istream&);        virtual double grade() const;    protected:        // accessible to derived classes        std::istream& read_common(std::istream&);        double midterm,final;        std::vector<double> homework;    private:        // accessible only to Core        std::string n;};std::istream& read_hw(std::istream&, std::vector<double>&);double grade(double, double, std::vector<double>);bool compare(const Core*, const Core*);#endif

Core.cpp

// source file Core-related#include "Core.h"#include "/home/rhk/workspace/4_grade/median.h"using std::string;  using std::vector;using std::istream;string Core::name() const { return n; }double Core::grade() const {    return ::grade(midterm, final, homework);}istream& Core::read_common(istream& in) {    // read and store the student's name and exam grades    in >> n >> midterm >> final;    return in;}istream& Core::read(istream& in) {    read_common(in);    read_hw(in, homework);    return in;}double grade(double midterm, double final, vector<double> homework) {    return 0.2 * midterm + 0.4 * final + 0.4 * median(homework);}// read homworksistream& read_hw(istream& in, vector<double>& hw) {    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;}bool compare(const Core* cp1, const Core* cp2) {    return cp1->name() < cp2->name();}

Grad.h

#ifndef GUARD_grad_h#define GUARD_grad_h#include "Core.h"class Grad:public Core {    public:        Grad(): thesis(0) { }        Grad(std::istream& is) { read(is); }        double grade() const;        std::istream& read(std::istream&);    private:        double thesis;};#endif

Grad.cpp

// source file of Grad-related#include "Core.h"#include "Grad.h"#include <algorithm>using std::istream;using std::min;istream& Grad::read(istream& in) {    read_common(in);    in >> thesis;    read_hw(in, homework);    return in;}double Grad::grade() const {    return min(Core::grade(), thesis);}

func.h

#ifndef GUARD_func_h#define GUARD_func_h#include <iostream>std::istream& read_hw(std::istream&, std::vector<double>&);#endif

func.cpp

// source file for functions#include "func.h"using std::istream; using std::vector;istream& read_hw(istream& in, vector<double>& hw) {    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;}

main.cpp

#include "Core.h"#include "Grad.h"#include <algorithm>#include <ios>#include <iomanip>#include <stdexcept>using std::string;  using std::cout;    using std::cin;using std::endl; using std::vector; using std::max;using std::streamsize;  using std::sort;    using std::setprecision;    using std::domain_error;int main() {    vector<Core*> students;    Core* record;    char ch;    string::size_type maxlen = 0;    while (cin >> ch) {        if (ch == 'U')            record = new Core;        else             record = new Grad;        record->read(cin);        maxlen = max(maxlen, record->name().size());        students.push_back(record);    }    sort(students.begin(), students.end(), compare);    for (vector<Grad>::size_type i = 0; i < students.size(); ++i) {        cout << students[i]->name() << string(maxlen + 1 - students[i]->name().size(), ' ');        try {            double final_grade = students[i]->grade();            streamsize prec = cout.precision();            cout << setprecision(3) << final_grade <<                     setprecision(prec) << endl;        } catch (domain_error e) {            cout << e.what() << endl;        }    }    return 0;}