has-a関係-多重私有継承

#ifndef _STUDENT_H_

#define _STUDENT_H_



#include <iostream>

#include <string>

#include <valarray>



class Student : private std::string, private std::valarray<double>

{

private:

    typedef std::valarray<double> ArrayDb;



    //private method for scores output

    std::ostream & arr_out(std::ostream & os) const;



public:

    Student()                                           : std::string("Null Student"),  ArrayDb()       {}

    explicit Student(const std::string & s)             : std::string(s),               ArrayDb()       {}

    explicit Student(int n)                             : std::string("Nully"),         ArrayDb(n)      {}

    Student(const std::string & s, int n)               : std::string(s),               ArrayDb(n)      {}

    Student(const std::string & s, const ArrayDb & a)   : std::string(s),               ArrayDb(a)      {}

    Student(const char * str, const double * pd, int n) : std::string(str),             ArrayDb(pd, n)  {}

    ~Student() {}



    double Average(void) const;

    const std::string & Name(void) const;

    //double & operator[](int i);

    //const double & operator[](int i) const;

    using std::valarray<double>::operator[];    // using 



    //friends

    //inout

    friend std::istream & operator>>(std::istream & is, Student & stu); //1 word

    friend std::istream & getline(std::istream & is, Student & stu);    //1 line

    //output

    friend std::ostream & operator<<(std::ostream & os, const Student & stu);

};



#endif

#include "student.h"

using std::ostream;

using std::istream;

using std::endl;

using std::string;



//public methods

double Student::Average(void) const

{

    if(ArrayDb::size() > 0)

    {

        return ArrayDb::sum() / ArrayDb::size();

    }

    else

    {

        return 0;

    }

}



const string & Student::Name(void) const

{

    return (const string &)*this;

}

/*

double & Student::operator[](int i)

{

    return ArrayDb::operator[](i);

}



const double & Student::operator[](int i) const

{

    return ArrayDb::operator[](i);

}

*/

//private method

ostream & Student::arr_out(ostream & os) const

{

    int i;

    if(ArrayDb::size() > 0)

    {

        for(i = 0; i < ArrayDb::size(); i++)

        {

            //os << ArrayDb::operator[](i) << " ";

            os << ((const ArrayDb &)*this)[i] << " ";

            if(i % 5 == 4)

            {

                os << endl;

            }

        }

        if(i % 5 != 0)

        {

            os << endl;

        }

    }

    else

    {

        os << "empty array";

    }

    return os;

}



//friend methods

istream & operator>>(istream & is, Student & stu)

{

    is >> (string &)stu;

    return is;

}



istream & getline(istream & is, Student & stu)

{

    getline(is, (string &)stu);

    return is;

}



ostream & operator<<(ostream & os, const Student & stu)

{

    os << "Scores for " << (const string &)stu << ":
";

    stu.arr_out(os);

    return os;

}

#include <iostream>

#include "student.h"

using std::cin;

using std::cout;

using std::endl;



void set(Student & sa, int n)

{

    cout << "Please enter the student's name: ";

    getline(cin, sa);

    cout << "Please enter " << n << " quiz scores:
";

    for(int i = 0; i < n; i++)

    {

        cin >> sa[i];

    }

    while(cin.get() != '
')

    {

        continue;

    }

}



const int pupils = 3;

const int quizzes = 5;



int main(void)

{

    Student ada[pupils] = {Student(quizzes), Student(quizzes), Student(quizzes)};



    for(int i = 0; i < pupils; i++)

    {

        set(ada[i], quizzes);

    }

    cout << "
Student List:
";

    for(int i = 0; i < pupils; i++)

    {

        cout << ada[i].Name() << endl;

    }

    cout << "
Results:";

    for(int i = 0; i < pupils; i++)

    {

        cout << endl << ada[i];

        cout << "average: " << ada[i].Average() << endl;

    }

    cout << "Done.
";



    return 0;

}