实验6 模板类、文件I/O和异常处理

task 4

代码：

Vector.hpp

#pragma once
#include <iostream>

using namespace std;

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

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

    template<typename T>
    friend void output(const Vector<T>& vi);

private:
    int size;
    T* ptr;
};

template<typename T>
Vector<T>::Vector(int n) {
    if (n < 0)
        throw length_error("Vector<T>::Vector(int)大小为负数");

    ptr = new T[n];
    size = n;
}

template<typename T>
Vector<T>::Vector(int n, T value) {
    if (n < 0)
        throw length_error("Vector<T>::Vector(int, T)大小为负数");

    ptr = new T[n];
    size = n;
    for (auto i = 0; i < n; i++) {
        ptr[i] = value;
    }
}

template<typename T>
Vector<T>::Vector(const Vector<T>& vi) {
    ptr = new T[vi.get_size()];

    for (auto i = 0; i < vi.get_size(); i++) {
        ptr[i] = vi[i];
    }

    size = vi.get_size();
}

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

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

template<typename T>
T& Vector<T>::at(int index) const {
    if (index < 0 || index >= size)
        throw out_of_range("Vector<T>::at()下标越界");

    return ptr[index];
}

template<typename T>
T& Vector<T>::operator[](int index) const {
    if (index < 0 || index >= size)
        throw out_of_range("Vector<T>::operator[]()下标越界");
    return ptr[index];
}

template<typename T>
void output(const Vector<T>& vi) {
    for (int i = 0; i < vi.get_size(); i++) {
        cout << vi.at(i) << " ";
    }
    cout << "\b \n";
}

 

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：

 

task 5

代码：

task5.cpp

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

using namespace std;

class Stu {
public:
    int get_score() const { return score; }
    string get_major() const { return major; }

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

private:
    string id;
    string name;
    string major;
    int score;
};

istream& operator>>(istream& in, Stu& s) {
    in >> s.id >> s.name >> s.major >> s.score;

    return in;
}

ostream& operator<<(ostream& out, const Stu& s) {
    out << setiosflags(ios_base::left);
    out << setw(15) << s.id
        << setw(15) << s.name
        << setw(15) << s.major
        << setw(15) << s.score;

    return out;
}

bool compare_by_solutionInfo(const Stu& s1, const Stu& 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<Stu> &s) {
    for (auto &i : s) {
        out << i << endl;
    }
}

void save(const string& filename, vector<Stu> &s) {
    ofstream out(filename);
    if (!out.is_open()) {
        cout << "fail to open file to write\n";
        return;
    }

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

void load(const string& filename, vector<Stu> &s) {
    ifstream in(filename);
    if (!in.is_open()) {
        cout << "fail to open file to read\n";
        return;
    }

    string title_line;
    getline(in, title_line);

    Stu t;
    while (in >> t) {
        s.push_back(t);
    }

    in.close();
}

int main() {
    vector<Stu> s;

    load("data5.txt", s);
    sort(s.begin(), s.end(), compare_by_solutionInfo);
    output(cout, s);
    save("ans.txt", s);

}

 

运行结果截图：