题目描述 要计算一个学生的 GPA，先将每门学科的等第换算成为一个绩点，规则为： 等第 A 为 4 4 分； 等第 B 为 3 3 分； 等第 C 为 2 2 分； 等第 D 为 1 1 分； 如果有 + 号后缀，则加 0.3 0.3 分。例如 B+ 为 3.3 3.3 分； 如果有 - 号后缀，则减 0.3 0.3 分。例如 C- 为 1.7 1.7 分。 接下来，再计算这些分数的平均数，四舍五入保留两位小数即可获得 GPA。 给定一个字符序列表示小爱每门课程的等第，请计算她的GPA。 输入格式 一个字符序列：表示小爱各门课程的等第，一门课程的等第只可能是 A、B、C、D 中的一个，保证 + 号或 - 号只会出现在字母的后面。 输出格式 一个两位小数：表示输入等第对应的 GPA。 数据范围 1≤n≤1000。

```cpp #include <iostream> #include <string> using namespace std; class Course { protected: string courseID; int credit; public: Course(string id, int c) : courseID(id), credit(c) {} virtual double totalS() = 0; virtual double GPA() = 0; int get_credit() { return credit; } }; class AdvanceMathematic : public Course { private: int exam; int dailywork; public: AdvanceMathematic(string id, int c, int e, int d) : Course(id, c), exam(e), dailywork(d) {} double totalS() { return exam * 0.6 + dailywork * 0.4; } double GPA() { return totalS() / 10.0 - 5; } }; class English : public Course { private: int exam; int dailywork; public: English(string id, int c, int e, int d) : Course(id, c), exam(e), dailywork(d) {} double totalS() { return exam * 0.7 + dailywork * 0.3; } double GPA() { return totalS() / 10.0 - 5; } }; class Cprogram : public Course { private: int exam; int dailywork; public: Cprogram(string id, int c, int e, int d) : Course(id, c), exam(e), dailywork(d) {} double totalS() { return exam * 0.5 + dailywork * 0.5; } double GPA() { return totalS() / 10.0 - 5; } }; int main() { Course* courses[3]; courses[0] = new AdvanceMathematic("1001", 4, 80, 90); courses[1] = new English("1002", 3, 80, 60); courses[2] = new Cprogram("1003", 3, 100, 90); double total_GPA = 0; int total_credit = 0; for (int i = 0; i < 3; i++) { cout << "课程ID: " << courses[i]->courseID << endl; cout << "学分: " << courses[i]->get_credit() << endl; cout << "总分: " << courses[i]->totalS() << endl; cout << "绩点: " << courses[i]->GPA() << endl << endl; total_GPA += courses[i]->GPA() * courses[i]->get_credit(); total_credit += courses[i]->get_credit(); } double avg_GPA = total_GPA / total_credit; cout << "平均绩点: " << avg_GPA << endl; return 0; } ```

实验题目：某学校教学系统中可以对学生的分数及绩点进行计算，张三同学的成绩如下表： | 课程 | 课程ID | 学分 | 考试成绩与平时成绩比例 | 绩点 | | -------- | ------ | ---- | ---------------------- | ---- | | 高数 | 1001 | 80 | 6:4 | | | 大学英语 | 1002 | 80 | 7:3 | | | C语言 | 1003 | 100 | 5:5 | | (1)设计一个基类Course,包含private数据成员课程ID、学分credit ; public函数get_creit用于读取credit的值，两个纯虚函数:总分计算totalS,课程绩点计算GPA ```cpp #include<iostream> #include<cmath> using namespace std; class Course { protected: int courseID; double credit; public: void get_credit() { // 读取credit的值 cout << "请输入课程学分：" << endl; cin >> credit; } virtual double totalS() = 0; // 纯虚函数，计算总分 virtual double GPA() = 0; // 纯虚函数，计算绩点 }; ``` (2)编写三个子类:高数AdvanceMathematic、英语English、C语言Cprogram公有继承基类Course。每个类都两个私有属性考试分数exam,平时分数dailywork。 ```cpp class AdvanceMathematic : public Course { private: double exam; double dailywork; public: AdvanceMathematic(double e, double d) : exam(e), dailywork(d) {} double totalS() { return exam * 0.6 + dailywork * 0.4; } double GPA() { double score = totalS(); if (score >= 90) return 4.0; else if (score >= 85) return 3.7; else if (score >= 82) return 3.3; else if (score >= 78) return 3.0; else if (score >= 75) return 2.7; else if (score >= 72) return 2.3; else if (score >= 68) return 2.0; else if (score >= 64) return 1.5; else if (score >= 60) return 1.0; else return 0; } }; class English : public Course { private: double exam; double dailywork; public: English(double e, double d) : exam(e), dailywork(d) {} double totalS() { return exam * 0.7 + dailywork * 0.3; } double GPA() { double score = totalS(); if (score >= 90) return 4.0; else if (score >= 85) return 3.7; else if (score >= 82) return 3.3; else if (score >= 78) return 3.0; else if (score >= 75) return 2.7; else if (score >= 72) return 2.3; else if (score >= 68) return 2.0; else if (score >= 64) return 1.5; else if (score >= 60) return 1.0; else return 0; } }; class Cprogram : public Course { private: double exam; double dailywork; public: Cprogram(double e, double d) : exam(e), dailywork(d) {} double totalS() { return exam * 0.5 + dailywork * 0.5; } double GPA() { double score = totalS(); if (score >= 90) return 4.0; else if (score >= 85) return 3.7; else if (score >= 82) return 3.3; else if (score >= 78) return 3.0; else if (score >= 75) return 2.7; else if (score >= 72) return 2.3; else if (score >= 68) return 2.0; else if (score >= 64) return 1.5; else if (score >= 60) return 1.0; else return 0; } }; ``` (3)每门课程绩点的计算方法为: GPA = 总分/10.0-5; 平均绩点计算方法为:平均绩点=Σ(学分×GPA)÷Σ学分 ```cpp int main() { AdvanceMathematic am(80, 90); English eng(80, 0); Cprogram cp(90, 90); double totalCredit = am.credit + eng.credit + cp.credit; double totalScore = am.totalS() * am.credit + eng.totalS() * eng.credit + cp.totalS() * cp.credit; double averageGPA = (am.GPA() * am.credit + eng.GPA() * eng.credit + cp.GPA() * cp.credit) / totalCredit; cout << "张三同学的总分为：" << totalScore << endl; cout << "张三同学的平均绩点为：" << averageGPA << endl; return 0; } ``` 完整代码如下： ```cpp #include<iostream> #include<cmath> using namespace std; class Course { protected: int courseID; double credit; public: void get_credit() { // 读取credit的值 cout << "请输入课程学分：" << endl; cin >> credit; } virtual double totalS() = 0; // 纯虚函数，计算总分 virtual double GPA() = 0; // 纯虚函数，计算绩点 }; class AdvanceMathematic : public Course { private: double exam; double dailywork; public: AdvanceMathematic(double e, double d) : exam(e), dailywork(d) {} double totalS() { return exam * 0.6 + dailywork * 0.4; } double GPA() { double score = totalS(); if (score >= 90) return 4.0; else if (score >= 85) return 3.7; else if (score >= 82) return 3.3; else if (score >= 78) return 3.0; else if (score >= 75) return 2.7; else if (score >= 72) return 2.3; else if (score >= 68) return 2.0; else if (score >= 64) return 1.5; else if (score >= 60) return 1.0; else return 0; } }; class English : public Course { private: double exam; double dailywork; public: English(double e, double d) : exam(e), dailywork(d) {} double totalS() { return exam * 0.7 + dailywork * 0.3; } double GPA() { double score = totalS(); if (score >= 90) return 4.0; else if (score >= 85) return 3.7; else if (score >= 82) return 3.3; else if (score >= 78) return 3.0; else if (score >= 75) return 2.7; else if (score >= 72) return 2.3; else if (score >= 68) return 2.0; else if (score >= 64) return 1.5; else if (score >= 60) return 1.0; else return 0; } }; class Cprogram : public Course { private: double exam; double dailywork; public: Cprogram(double e, double d) : exam(e), dailywork(d) {} double totalS() { return exam * 0.5 + dailywork * 0.5; } double GPA() { double score = totalS(); if (score >= 90) return 4.0; else if (score >= 85) return 3.7; else if (score >= 82) return 3.3; else if (score >= 78) return 3.0; else if (score >= 75) return 2.7; else if (score >= 72) return 2.3; else if (score >= 68) return 2.0; else if (score >= 64) return 1.5; else if (score >= 60) return 1.0; else return 0; } }; int main() { AdvanceMathematic am(80, 90); English eng(80, 0); Cprogram cp(90, 90); double totalCredit = am.credit + eng.credit + cp.credit; double totalScore = am.totalS() * am.credit + eng.totalS() * eng.credit + cp.totalS() * cp.credit; double averageGPA = (am.GPA() * am.credit + eng.GPA() * eng.credit + cp.GPA() * cp.credit) / totalCredit; cout << "张三同学的总分为：" << totalScore << endl; cout << "张三同学的平均绩点为：" << averageGPA << endl; return 0; } ```