实验6 模板类、文件I/O和异常处理

实验内容4

Vector.hpp

#pragma once
#include<iostream>
#include<stdexcept>

using namespace std;

template<typename T>

class Vector {
    private:
        int size;
        T* ptr;
        
    public:
        Vector(int size, int value = 0) :size { size } {
            if (size < 0) {
                throw length_error("Vector constructor: negative size");
            }
            ptr = new T[size];
            for (int i = 0; i < size; i++) {
                ptr[i] = value;
            }
        }
        int get_size() const {
            return size;
        }
        T& at(int index) const {
            if (index < 0 || index >= size) throw out_of_range("Vector: index out of range");
            return ptr[index];
        }
        T& at(int index) {
            return static_cast<const Vector<T>*>(this)->at(index);
        }
        T& operator[](int index)const {
            if (index < 0 || index >= size) throw out_of_range("Vector: index out of range");
            return ptr[index];
        }
        T& operator[](int index) {
            return static_cast<const Vector<T>*>(this)->operator[](index);
        }
};

template<typename T1>
void output(const Vector<T1>& v) {
    for (int i = 0; i < v.get_size(); i++) {
        cout << v[i] << ", ";
    }
    cout << endl;
}

 

task4.cpp

#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();
}

 

运行结果截图

 

实验内容5

task5.cpp

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

using namespace std;

class student{
public:
    student() = default;
    ~student() = default;

    string get_major()const {
        return major;
    }

    int get_score()const {
        return score;
    }

    friend ostream& operator<<(ostream& out, const student& s) {
        out << setiosflags(ios_base::left);
        out << setw(10) << s.number
            << setw(10) << s.name
            << setw(10) << s.major
            << setw(10) << s.score;

        return out;
    }

    friend istream& operator>>(istream& in,  student& s) {
        in >>s.number >> s.name >> s.major >> s.score;

        return in;
    }

private:
    string number;
    string name;
    string major;
    int score;

};

bool compare(const student& s1, const student& s2) {
    if (s1.get_major() < s2.get_major())
        return true;

    if (s1.get_major() == s2.get_major())
        return s1.get_score() > s2.get_score();

    return false;
}

void output(ostream& out, const vector<student>& v) {
    for (auto& i : v)
        out << i << endl;
}

void save(const string& filename, vector<student>& v) {
    ofstream out(filename);
    if (!out.is_open()) {
        cout << "写入文件失败\n";
        return;
    }

    output(out, v);
    out.close();
}

void load(const string& filename, vector<student>& v) {
    ifstream in(filename);
    if (!in.is_open()) {
        cout << "读取文件失败\n";
        return;
    }

    string title_line;
    getline(in, title_line);

    student t;
    while (in >> t)
        v.push_back(t);

    in.close();
}

int main() {
    vector<student>v;

    load("data5.txt", v);
    sort(v.begin(), v.end(), compare);
    output(cout, v);
    save("ans5.txt", v);
}

 

运行结果显示：