添加复用

base/CMakeLists.txt

@@ -53,4 +53,7 @@ add_executable(useStock20 class/useStock20.cpp)
 add_executable(namessp namespacetest/namessp.cpp)
 add_executable(string new/string.cpp)
 add_executable(placenew new/placenew.cpp)
-add_executable(usett extend/usett.cpp)
+add_executable(usett extend/usett.cpp)
+add_executable(test5_1 test5.cpp)
+add_executable(studentc reusing/studentc.cpp)
+add_executable(uses_stuc reusing/uses_stuc.cpp)

base/reusing/studentc.cpp

@@ -0,0 +1,68 @@
+//
+// Created by zhuyijun on 2021/8/30.
+//
+
+#include "studentc.h"
+
+using std::ostream;
+using std::endl;
+using std::istream;
+using std::string;
+
+/**
+ * 求平均值
+ * @return double
+ */
+double Student::Average() const {
+    if (scores.size() > 0) {
+        return scores.sum() / scores.size();
+    }
+    return 0;
+}
+
+const std::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(std::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;
+}
+

base/reusing/studentc.h

@@ -0,0 +1,48 @@
+//
+// Created by zhuyijun on 2021/8/30.
+//
+
+#ifndef BASE_STUDENTC_H
+#define BASE_STUDENTC_H
+
+#include <iostream>
+#include <string>
+#include <valarray>
+
+class Student {
+private:
+    //使用typedef 对std::valarray<double>进行简化表达
+    typedef std::valarray<double> ArrayDb;
+    std::string name;
+    ArrayDb scores;
+    std::ostream & arr_out(std::ostream & os) const;
+
+public:
+    Student() :name("Null Student"),scores() {}
+    /**
+     * C++中的explicit关键字只能用于修饰只有一个参数的类构造函数,
+     * 它的作用是表明该构造函数是显示的, 而非隐式的,
+     * 跟它相对应的另一个关键字是implicit, 意思是隐藏的,
+     * 类构造函数默认情况下即声明为implicit(隐式)
+     * @param s
+     */
+    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;
+
+    //友元
+    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 //BASE_STUDENTC_H

base/reusing/uses_stuc.cpp

@@ -0,0 +1,42 @@
+//
+// Created by zhuyijun on 2021/8/30.
+//
+
+#include <iostream>
+#include "studentc.h"
+using namespace std;
+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}
+    };
+    for (int i = 0; i < pupils; ++i) {
+        set(ada[i],quizzes);
+    }
+    cout <<"\nStudent List:\n";
+    for (int i = 0; i < pupils; ++i) {
+        cout <<ada[i].Name() << endl;
+    }
+    cout <<"\nResult:";
+    for (int 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;
+    }
+}
+

base/test5.cpp

@@ -0,0 +1,11 @@
+//
+// Created by zhuyijun on 2021/8/4.
+//
+
+#include <iostream>
+using namespace std;
+int main() {
+    int a = 010 & 001;
+    cout << a;
+    return 0;
+}