update 14 chapter context

Author: lulongfei

chapter14/context/14.1studentc.cpp

@@ -0,0 +1,74 @@
+#include "14.1studentc.h"
+using std::ostream;
+using std::endl;
+using std::istream;
+using std::string;
+
+double Student::Average() const
+{
+    if (scores.size() > 0)
+        return scores.sum() / scores.size();
+    else
+        return 0;
+}
+
+
+const string & Student::Name() const
+{
+    return name;
+}
+
+
+double & Student::operator[](int i)
+{
+    return scores[i];
+}
+
+
+double Student::operator[](int i) const
+{
+    return scores[i];
+}
+
+
+ostream & Student::arr_out(ostream & os) const
+{
+    int i;
+    int lim = scores.size();
+    if (lim > 0)
+    {
+        for(i = 0; i < lim; i++)
+        {
+            os << scores[i] << " ";
+            if ( i % 5 == 4 )
+                os << endl;
+        }
+        if(i % 5 != 0)
+            os << endl;
+    }
+    else
+        os << " empty array";
+    return os;
+}
+
+
+istream & operator>>(istream & is, Student & stu)
+{
+    is >> stu.name;
+    return is;
+}
+
+
+istream & getline(istream & is, Student & stu)
+{
+    getline(is, stu.name);
+    return is;
+}
+
+
+ostream & operator<<(ostream & os, const Student & stu)
+{
+    os << "Scores for " << stu.name << ":\n";
+    stu.arr_out(os);
+    return os;
+}

chapter14/context/14.1studentc.h

@@ -0,0 +1,41 @@
+#ifndef STUDENTC_H_
+#define STUDENTC_H_
+
+#include <iostream>
+#include <string>
+#include <valarray>
+
+
+class Student
+{
+    private:
+        typedef std::valarray<double> ArrayDb;
+        std::string name;
+        ArrayDb scores;
+        std::ostream & arr_out(std::ostream & os) const;
+    public:
+        Student(): name("Null Student"), scores(){}
+        explicit Student(const std::string & s)
+            :name(s), scores(){}
+        explicit Student(int n): name("Nully"), scores(n){}
+        Student(const std::string & s, int n)
+            :name(s), scores(n){}
+        Student(const std::string & s, const ArrayDb & a)
+            :name(s), scores(a){}
+        Student(const char * str, const double * pd, int n)
+            :name(str), scores(pd, n) {}
+
+        ~Student() {}
+
+        double Average() const;
+        const std::string & Name() const;
+        double & operator[] (int i);
+        double operator[](int i) const;
+
+        friend std::istream & operator>>(std::istream & is, Student & stu);
+        friend std::istream & getline(std::istream & is, Student & stu);
+        friend std::ostream & operator<<(std::ostream & os, const Student & stu);
+
+};
+
+#endif

chapter14/context/14.1use_stuc.cpp

@@ -0,0 +1,54 @@
+#include "14.1studentc.h"
+#include <iostream>
+
+
+using std::cin;
+using std::cout;
+using std::endl;
+
+void set(Student & sa, int n);
+const int pupils = 3;
+const int quizzes = 5;
+
+int main()
+{
+    Student ada[pupils] = {Student(quizzes), Student(quizzes), Student(quizzes)};
+    int i;
+    for(i = 0; i < pupils; i++)
+    {
+        set(ada[i], quizzes);
+    }
+
+    cout << "\nStudent List: \n";
+    for(i = 0; i < pupils; ++i)
+    {
+        cout << ada[i].Name() << endl;
+    }
+
+    cout << "\nResult: ";
+
+    for(i = 0; i < pupils; ++i)
+    {
+        cout << endl << ada[i];
+        cout << "average: " << ada[i].Average() << endl;
+    }
+
+    cout << "Done.\n";
+    return 0;
+}
+
+
+void set(Student & sa, int n)
+{
+    cout << "Please enter the student's name: ";
+    getline(cin, sa);
+    cout << "Please enter " << n << " quiz scores: \n";
+    for(int i = 0; i < n; i++)
+    {
+        cin >> sa[i];
+    }
+    while (cin.get() != '\n')
+        continue;
+}
+
+