实验6 模板类、文件I/O和异常处理

实验任务4

#ifndef VECTOR_HPP
#define VECTOR_HPP

#include <iostream>
#include <stdexcept>

template<typename T>
class Vector {
private:
    T* data;
    size_t size;

public:
    // 构造函数，动态指定大小
    Vector(size_t n) {
        if (n < 0) {
            std::cerr << "Vector constructor: negative size" << std::endl;
        }
        size = n;
        data = new T[size];
    }

    // 构造函数，动态指定大小并初始化每个数据项
    Vector(size_t n, const T& value) {
        if (n < 0) {
            std::cerr << "Vector constructor: negative size" << std::endl;
        }
        size = n;
        data = new T[size];
        for (size_t i = 0; i < size; ++i) {
            data[i] = value;
        }
    }

    // 深拷贝构造函数
    Vector(const Vector& other) {
        size = other.size;
        data = new T[size];
        for (size_t i = 0; i < size; ++i) {
            data[i] = other.data[i];
        }
    }

    // 析构函数
    ~Vector() {
        delete[] data;
    }

    // 返回动态数组对象中数据项个数
    size_t get_size() const {
        return size;
    }

    // at() 方法，支持下标访问并处理越界异常
    T& at(size_t i) {
        if (i >= size) {
            throw std::out_of_range("Index out of range");
        }
        return data[i];
    }

    const T& at(size_t i) const {
        if (i >= size) {
            throw std::out_of_range("Index out of range");
        }
        return data[i];
    }

    // 重载 [] 运算符
    T& operator[](size_t i) {
        return at(i);
    }

    const T& operator[](size_t i) const {
        return at(i);
    }

    // 友元函数，用于输出 Vector 对象中的数据项
    friend void output(const Vector& vec) {
        for (size_t i = 0; i < vec.size; ++i) {
            std::cout << vec.data[i] << " ";
        }
        std::cout << std::endl;
    }
};

#endif // VECTOR_HPP

#include <iostream>
#include "Vector.hpp"

void test1() {
    using namespace std;

    int n;
    cout << "Enter n: ";
    cin >> n;
    
    Vector<double> x1(n);
    for(auto i = 0; i < n; ++i)
        x1.at(i) = i * 0.7;

    cout << "x1: "; output(x1);

    Vector<int> x2(n, 42);
    const Vector<int> x3(x2);

    cout << "x2: "; output(x2);
    cout << "x3: "; output(x3);

    x2.at(0) = 77;
    x2.at(1) = 777;
    cout << "x2: "; output(x2);
    cout << "x3: "; output(x3);
}

void test2() {
    using namespace std;

    int n, index;
    while(cout << "Enter n and index: ", cin >> n >> index) {
        try {
            Vector<int> v(n, n);
            v.at(index) = -999;
            cout << "v: "; output(v);
        }
        catch (const exception &e) {
            cout << e.what() << endl;
        }
    }
}

int main() {
    using namespace std;
    cout << "测试1: 模板类接口测试\n";
    test1();

    cout << "\n测试2: 模板类异常处理测试\n";
    test2();
}

 

运行测试截图

 

实验任务5

#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <algorithm>
#include <string>

// 定义学生结构体
struct Student {
    std::string id;
    std::string name;
    std::string major;
    int score;
};

// 比较函数，用于按专业字典序和分数降序排序
bool compareStudents(const Student& a, const Student& b) {
    if (a.major != b.major) {
        return a.major < b.major; // 先按专业字典序排序
    } else {
        return a.score > b.score; // 专业相同时，按分数降序排序
    }
}

// 从文件中读取学生数据
std::vector<Student> readStudentsFromFile(const std::string& filename) {
    std::vector<Student> students;
    std::ifstream file(filename);
    std::string line;

    // 跳过标题行
    if (std::getline(file, line)) {
        while (std::getline(file, line)) {
            std::istringstream iss(line);
            Student student;
            std::getline(iss, student.id, '\t');
            std::getline(iss, student.name, '\t');
            std::getline(iss, student.major, '\t');
            std::getline(iss, line, '\t'); // 读取分数前的制表符和分数后的换行符或空格等
            std::stringstream ss(line);
            ss >> student.score;
            students.push_back(student);
        }
    }

    file.close();
    return students;
}

// 将学生数据写入文件
void writeStudentsToFile(const std::vector<Student>& students, const std::string& filename) {
    std::ofstream file(filename);
    file << "学号\t姓名\t专业\t分数" << std::endl;
    for (const auto& student : students) {
        file << student.id << "\t" << student.name << "\t" << student.major << "\t" << student.score << std::endl;
    }
    file.close();
}

// 打印学生数据到屏幕
void printStudentsToScreen(const std::vector<Student>& students) {
    for (const auto& student : students) {
        std::cout << student.id << "\t" << student.name << "\t" << student.major << "\t" << student.score << std::endl;
    }
}

int main() {
    std::vector<Student> students = readStudentsFromFile("data5.txt");

    // 对学生数据进行排序
    std::sort(students.begin(), students.end(), compareStudents);

    // 打印排序后的学生数据到屏幕
    printStudentsToScreen(students);

    // 将排序后的学生数据写入文件
    writeStudentsToFile(students, "ans5.txt");

    return 0;
}

 

运行测试截图