#include <iostream> #include <string> #include "GradeCalc.hpp"void test() {GradeCalc c1("OOP");std::cout << "录入成绩:\n";c1.input(5);std::cout << "输出成绩:\n";c1.output();std::cout << "排序后成绩:\n";c1.sort(); c1.output();std::cout << "*************成绩统计信息*************\n";c1.info();}int main() {test(); }
GradeCalc.hpp：
#pragma once#include <vector> #include <array> #include <string>class GradeCalc { public:GradeCalc(const std::string &cname); void input(int n); // 录入n个成绩void output() const; // 输出成绩void sort(bool ascending = false); // 排序 (默认降序)int min() const; // 返回最低分（如成绩未录入，返回-1)int max() const; // 返回最高分 （如成绩未录入，返回-1)double average() const; // 返回平均分 （如成绩未录入，返回0.0)void info(); // 输出课程成绩信息 private:void compute(); // 成绩统计private:std::string course_name; // 课程名std::vector<int> grades; // 课程成绩std::array<int, 5> counts; // 保存各分数段人数（[0, 60), [60, 70), [70, 80), [80, 90), [90, 100]std::array<double, 5> rates; // 保存各分数段人数占比 bool is_dirty; // 脏标记，记录是否成绩信息有变更 };
GradeCalc.cpp：
#include <algorithm> #include <array> #include <cstdlib> #include <iomanip> #include <iostream> #include <numeric> #include <string> #include <vector>#include "GradeCalc.hpp"GradeCalc::GradeCalc(const std::string &cname):course_name{cname},is_dirty{true} {counts.fill(0);rates.fill(0); }void GradeCalc::input(int n) {if(n < 0) {std::cerr << "无效输入! 人数不能为负数\n";std::exit(1);}grades.reserve(n);int grade;for(int i = 0; i < n;) {std::cin >> grade;if(grade < 0 || grade > 100) {std::cerr << "无效输入! 分数须在[0,100]\n";continue;}grades.push_back(grade);++i;}is_dirty = true; // 设置脏标记：成绩信息有变更 }void GradeCalc::output() const {for(auto grade: grades)std::cout << grade << ' ';std::cout << std::endl; }void GradeCalc::sort(bool ascending) {if(ascending)std::sort(grades.begin(), grades.end());elsestd::sort(grades.begin(), grades.end(), std::greater<int>()); }int GradeCalc::min() const {if(grades.empty())return -1;auto it = std::min_element(grades.begin(), grades.end());return *it; }int GradeCalc::max() const {if(grades.empty()) return -1;auto it = std::max_element(grades.begin(), grades.end());return *it; }double GradeCalc::average() const {if(grades.empty())return 0.0;double avg = std::accumulate(grades.begin(), grades.end(), 0.0)/grades.size();return avg; }void GradeCalc::info() {if(is_dirty) compute();std::cout << "课程名称:\t" << course_name << std::endl;std::cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << std::endl;std::cout << "最高分:\t" << max() << std::endl;std::cout << "最低分:\t" << min() << std::endl;const std::array<std::string, 5> grade_range{"[0, 60) ", "[60, 70)", "[70, 80)","[80, 90)", "[90, 100]"};for(int i = static_cast<int>(grade_range.size())-1; i >= 0; --i)std::cout << grade_range[i] << "\t: " << counts[i] << "人\t"<< std::fixed << std::setprecision(2) << rates[i]*100 << "%\n"; }void GradeCalc::compute() {if(grades.empty())return;counts.fill(0); rates.fill(0.0);// 统计各分数段人数for(auto grade:grades) {if(grade < 60)++counts[0]; // [0, 60)else if (grade < 70)++counts[1]; // [60, 70)else if (grade < 80)++counts[2]; // [70, 80)else if (grade < 90)++counts[3]; // [80, 90)else++counts[4]; // [90, 100] }// 统计各分数段比例for(size_t i = 0; i < rates.size(); ++i)rates[i] = counts[i] * 1.0 / grades.size();is_dirty = false; // 更新脏标记 }
问题1：std::string course_name 存储课程名称。
std::vector<int> grades 存储录入的所有成绩。
std::array<int, 5> counts 存储 5 个分数段的人数。
std::array<double, 5> rates 存储 5 个分数段的人数占比。
bool is_dirty 标记成绩是否有变更，控制统计计算是否执行。
问题2：不合法。input 拼写错误 ；还有grades是类的私有成员，无法直接访问 。
问题3：1：一次；仅当 is-dirty 值为 true时才会被调用一次。
2：不需要；
问题4：在info函数中加；
伪代码：
double median() const {if (grades.empty()) return 0;std::vector<int> temp = grades;std::sort(temp.begin(), temp.end());size_t n = temp.size();return n % 2 == 1 ? temp[n/2] : (temp[n/2 - 1] + temp[n/2]) / 2.0; }
问题5：不能去掉。去掉之后会多次调用compute，导致countd 和rates未重置数据，结果会一直累加，导致结果错误。
问题6：1：无功能影响。
2：有性能影响。会降低程序运行效率。
任务二：GradeCalc.hpp：
#pragma once#include <array> #include <string> #include <vector>class GradeCalc: private std::vector<int> { public:GradeCalc(const std::string &cname); void input(int n); // 录入n个成绩void output() const; // 输出成绩void sort(bool ascending = false); // 排序 (默认降序)int min() const; // 返回最低分int max() const; // 返回最高分double average() const; // 返回平均分void info(); // 输出成绩统计信息 private:void compute(); // 计算成绩统计信息private:std::string course_name; // 课程名std::array<int, 5> counts; // 保存各分数段人数（[0, 60), [60, 70), [70, 80), [80, 90), [90, 100]std::array<double, 5> rates; // 保存各分数段占比bool is_dirty; // 脏标记，记录是否成绩信息有变更 };
GradeCalc.cpp ：
#include <algorithm> #include <array> #include <cstdlib> #include <iomanip> #include <iostream> #include <numeric> #include <string> #include <vector> #include "GradeCalc.hpp"GradeCalc::GradeCalc(const std::string &cname): course_name{cname}, is_dirty{true}{counts.fill(0);rates.fill(0); } void GradeCalc::input(int n) {if(n < 0) {std::cerr << "无效输入! 人数不能为负数\n";return;}this->reserve(n);int grade;for(int i = 0; i < n;) {std::cin >> grade;if(grade < 0 || grade > 100) {std::cerr << "无效输入! 分数须在[0,100]\n";continue;}this->push_back(grade);++i;} is_dirty = true; } void GradeCalc::output() const {for(auto grade: *this)std::cout << grade << ' ';std::cout << std::endl; } void GradeCalc::sort(bool ascending) {if(ascending)std::sort(this->begin(), this->end());elsestd::sort(this->begin(), this->end(), std::greater<int>()); } int GradeCalc::min() const {if(this->empty())return -1;return *std::min_element(this->begin(), this->end()); } int GradeCalc::max() const {if(this->empty())return -1;return *std::max_element(this->begin(), this->end()); } double GradeCalc::average() const {if(this->empty())return 0.0;double avg = std::accumulate(this->begin(), this->end(), 0.0) / this->size();return avg; } void GradeCalc::info() {if(is_dirty) compute();std::cout << "课程名称:\t" << course_name << std::endl;std::cout << "平均分:\t" << std::fixed << std::setprecision(2) << average() << std::endl;std::cout << "最高分:\t" << max() << std::endl;std::cout << "最低分:\t" << min() << std::endl;const std::array<std::string, 5> grade_range{"[0, 60) ", "[60, 70)", "[70, 80)","[80, 90)", "[90, 100]"};for(int i = static_cast<int>(grade_range.size())-1; i >= 0; --i)std::cout << grade_range[i] << "\t: " << counts[i] << "人\t"<< std::fixed << std::setprecision(2) << rates[i]*100 << "%\n"; }void GradeCalc::compute() {if(this->empty())return;counts.fill(0);rates.fill(0);// 统计各分数段人数for(int grade: *this) {if(grade < 60)++counts[0]; // [0, 60)else if (grade < 70)++counts[1]; // [60, 70)else if (grade < 80)++counts[2]; // [70, 80)else if (grade < 90)++counts[3]; // [80, 90)else++counts[4]; // [90, 100] }// 统计各分数段比例for(size_t i = 0; i < rates.size(); ++i)rates[i] = counts[i] * 1.0 / this->size();is_dirty = false; }
task2.cpp：
#include <iostream> #include <string> #include "GradeCalc.hpp"void test() {GradeCalc c1("OOP");std::cout << "录入成绩:\n";c1.input(5);std::cout << "输出成绩:\n";c1.output();std::cout << "排序后成绩:\n";c1.sort(); c1.output();std::cout << "*************成绩统计信息*************\n";c1.info();}int main() {test(); }
问题一：class GradeCalc: private std::vector<int>
问题二：不会；不能；input 拼写错误 ；还有grades是类的私有成员，无法直接访问 。
问题三：组合：通过成员grades直接访问 ； 继承：通过this指针的基类接口（如迭代器、成员函数）访问
问题四：组合方案更合适；封装性更好。
任务三：Graph.hpp：
#pragma once#include <string> #include <vector>enum class GraphType {circle, triangle, rectangle};// Graph类定义 class Graph { public:virtual void draw() {}virtual ~Graph() = default; };// Circle类声明 class Circle : public Graph { public:void draw(); };// Triangle类声明 class Triangle : public Graph { public:void draw(); };// Rectangle类声明 class Rectangle : public Graph { public:void draw(); };// Canvas类声明 class Canvas { public:void add(const std::string& type); // 根据字符串添加图形void paint() const; // 使用统一接口绘制所有图形~Canvas(); // 手动释放资源private:std::vector<Graph*> graphs; };// 4. 工具函数 GraphType str_to_GraphType(const std::string& s); // 字符串转枚举类型 Graph* make_graph(const std::string& type); // 创建图形，返回堆对象指针
Graph.cpp：
#include <algorithm> #include <cctype> #include <iostream> #include <string>#include "Graph.hpp"// Circle类实现 void Circle::draw() { std::cout << "draw a circle...\n"; }// Triangle类实现 void Triangle::draw() { std::cout << "draw a triangle...\n"; }// Rectangle类实现 void Rectangle::draw() { std::cout << "draw a rectangle...\n"; }// Canvas类实现 void Canvas::add(const std::string& type) {Graph* g = make_graph(type);if (g) graphs.push_back(g); }void Canvas::paint() const {for (Graph* g : graphs) g->draw(); }Canvas::~Canvas() {for (Graph* g : graphs) delete g; }// 工具函数实现 // 字符串 → 枚举转换 GraphType str_to_GraphType(const std::string& s) {std::string t = s;std::transform(s.begin(), s.end(), t.begin(),[](unsigned char c) { return std::tolower(c);});if (t == "circle") return GraphType::circle;if (t == "triangle") return GraphType::triangle;if (t == "rectangle")return GraphType::rectangle;return GraphType::circle; // 缺省返回 }// 创建图形，返回堆对象指针 Graph* make_graph(const std::string& type) {switch (str_to_GraphType(type)) {case GraphType::circle: return new Circle;case GraphType::triangle: return new Triangle;case GraphType::rectangle: return new Rectangle;default: return nullptr;} }
task3.cpp：
#include <string> #include "Graph.hpp"void test() {Canvas canvas;canvas.add("circle");canvas.add("triangle");canvas.add("rectangle");canvas.paint(); }int main() {test(); }
问题一：1：std::vector<Graph*> graphs ；功能：存储对象指针；
2：class Circle : public Graph ； class Triangle : public Graph ；class Rectangle : public Graph
问题二：1：
2：
3：内存无法释放，导致内存泄漏；
问题三：新增 GraphType::star 枚举值；声明 class Star : public Graph { public: void draw(); }；
实现 Star::draw() 函数 ；在 str_to_GraphType 中添加分支 ；
问题四：1：在析构函数中调用delete函数的时候。
2：利：较为简单，无额外开销；弊：可能会因为操作不当导致内存泄露等问题。
任务四：demo4.cpp
#include "Toy.hpp"int main() {ToyFactory myFactory;myFactory.addToy(new LightToy("玩具小熊", "公仔", "蓝色的"));myFactory.addToy(new SoundToy("超级飞侠", "积木", "我是超人！"));myFactory.addToy(new LightToy("恐龙摆件", "饰品", "绿色的"));myFactory.showAllToys();return 0; }
Toy.cpp:
#include "Toy.hpp" #include <iostream>// 实现LightToy的特异功能 void LightToy::specialPower() {std::cout << name << " 发出了" << lightColor << "的光\n"; }// 实现SoundToy的特异功能 void SoundToy::specialPower() {std::cout << name << " 喊出了：" << soundContent << "\n"; }// ToyFactory的实现 void ToyFactory::addToy(Toy* toy) {toyList.push_back(toy); // 把玩具加入工厂的列表 }void ToyFactory::showAllToys() const {std::cout << "\n===== 玩具工厂清单 =====\n";for (const auto& toy : toyList) {// 显示玩具基础信息std::cout << "名称：" << toy->getName() << " | 类型：" << toy->getType() << " | 特异功能：";// 多态调用特异功能toy->specialPower();} }// 析构函数：释放所有玩具的内存 ToyFactory::~ToyFactory() {for (auto toy : toyList) {delete toy;} }
Toy.hpp:
#pragma once #include <string> #include <vector>class Toy { protected:std::string name;std::string type;public:Toy(std::string toyName, std::string toyType) : name(toyName), type(toyType) {}// 虚函数：特异功能virtual void specialPower() = 0;// 获取名称和接口std::string getName() const { return name; }std::string getType() const { return type; }// 虚析构函数virtual ~Toy() {} };// 子类1 class LightToy : public Toy { private:std::string lightColor; public:LightToy(std::string name, std::string type, std::string color): Toy(name, type), lightColor(color) {}void specialPower() override;std::string getLightColor() const { return lightColor; } };// 子类2 class SoundToy : public Toy { private:std::string soundContent;public:SoundToy(std::string name, std::string type, std::string sound): Toy(name, type), soundContent(sound) {}void specialPower() override;std::string getSound() const { return soundContent; } };//组合 class ToyFactory { private:std::vector<Toy*> toyList; //组合关系public:// 添加玩具到工厂void addToy(Toy* toy);// 显示所有玩具信息void showAllToys() const;// 析构函数：释放内存~ToyFactory(); };