实验6 模板类、文件I/O和异常处理

#pragma once
#include <iostream>
#include <stdexcept>
using namespace std;

template <typename T>
class Vector {
public:
    Vector(int size);
    Vector(int size, T value);
    Vector(const Vector<T>& other);
    ~Vector();                      


    int get_size() const; 
    T& at(int index);  
    const T& at(int index) const; 
    
    T& operator[](int index);
    const T& operator[](int index) const;

    template <typename U>
    friend void output(const Vector<U>& v);

private:
    int size; 
    T* data;
};

template <typename T>
Vector<T>::Vector(int size) : size(size) {
    if (size < 0) throw std::length_error("Vector constructor: negative size");
    data = new T[size]{};
}

template <typename T>
Vector<T>::Vector(int size, T value) : size(size) {
    if (size < 0) throw std::length_error("Vector constructor: negative size");
    data = new T[size];
    for (int i = 0; i < size; ++i) data[i] = value;
}

template <typename T>
Vector<T>::Vector(const Vector<T>& other) : size(other.size) {
    data = new T[size];
    for (int i = 0; i < size; ++i) data[i] = other.data[i];
}


template <typename T>
Vector<T>::~Vector() {
    delete[] data;
}

template <typename T>
int Vector<T>::get_size() const {
    return size;
}

template <typename T>
T& Vector<T>::at(int index) {
    if (index < 0 || index >= size) throw std::out_of_range("Vector: index out of range");
    return data[index];
}

template <typename T>
const T& Vector<T>::at(int index) const {
    if (index < 0 || index >= size) throw std::out_of_range("Vector: index out of range");
    return data[index];
}

template <typename T>
T& Vector<T>::operator[](int index) {
    return at(index);
}

template <typename T>
const T& Vector<T>::operator[](int index) const {
    return at(index);
}


template <typename U>
void output(const Vector<U>& v) {
    for (int i = 0; i < v.size; ++i) {
        std::cout << v.data[i] << " ";
    }
    std::cout << std::endl;
}

 #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() {
    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();
}

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

using namespace std;


class Student {
public:
    int id; 
    string name;
    string major; 
    int score; 

    friend istream& operator>>(istream& in, Student& s);
    friend ostream& operator<<(ostream& out, const Student& s);
};

istream& operator>>(istream& in, Student& s) {
    in >> s.id >> s.name >> s.major >> s.score;
    return in;
}
ostream& operator<<(ostream& out, const Student& s) {
    out << left << setw(10) << s.id
        << setw(10) << s.name
        << setw(10) << s.major
        << fixed << setprecision(2) << s.score;
    return out;
}

int main() {
    vector<Student> students;


    const string input_file = "data5.txt";
    const string output_file = "ans5.txt";

    ifstream infile(input_file);
    ofstream outfile(output_file);
    string header;
    getline(infile, header);

    Student temp;
    while (infile >> temp) {
        students.push_back(temp);
    }
    infile.close();

    sort(students.begin(), students.end(), [](const Student& a, const Student& b) {
        if (a.major == b.major) return a.score > b.score;
        return a.major < b.major;
    });

    for (const auto& s : students) {
        cout << s << endl;
    

        for (const auto& s : students) {
            outfile << s << endl;
        }
        outfile.close();
    }
    return 0;
}