实验六

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

template<typename T>
class Vector
{
private:
    int size;
    T* ptr;
public:
    //拷贝构造析构
    Vector(int n);
    Vector(int n, T value);
    Vector(const Vector<T>& v);
    ~Vector();

    int get_size(){return size;}

    //at
    T& at(int index)const;
    T& at(int index);

    //重载运算符[]
    T& operator[](int index)const;
    T& operator[](int index);

    //友元output
    template<typename T1>
    friend void output(const Vector<T1>& v);
};

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


template<typename T>
Vector<T>::Vector(int n, T value) :size(n)
{

    if (n < 0)
    {
        throw length_error("Vector constructor:negative size");
    }
    else
    {
        ptr = new T[size];
        for (int i = 0; i < size; i++)
        {
            ptr[i] = value;

        }
    }


}

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

}

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

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

}

template<typename T>
T& Vector<T>::at(int index)
{
    return static_cast<const Vector*>(this)->at(index);
}

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

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

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

#pragma once
#include<iostream>
#include<string>
#include<iomanip>

using namespace std;

class stu
{
private:
    int No;
    string name;
    string major;
    int score;

public:
    stu() = default;
    ~stu() = default;

    string get_major()const
    {
        return major;
    }
    int get_score()const
    {
        return score;
    }

    friend ostream& operator<<(ostream& out, stu& p);
    friend istream& operator>>(istream& in, stu& p);


};

ostream& operator<<(ostream& out, stu& p)
{
    out << setiosflags(ios_base::left);
    out << setw(15) << p.No
        << setw(15) << p.name
        << setw(15) << p.major
        << setw(15) << p.score << endl;
    return out;

}

istream& operator>>(istream& in, stu& p)
{
    in >> p.No >> p.name >> p.major >> p.score;
    return in;
}

#pragma once
#include"stu.hpp"
#include<iostream>
#include<string>
#include<fstream>
#include<vector>

bool compare(const stu& p1, const stu& p2)
{
    if (p1.get_major() < p2.get_major())
    {
        return true;
    }
    if (p1.get_major() == p2.get_major())
    {
        return p1.get_score() > p2.get_score();

    }
    return false;

}

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

}

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

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

}

void load(const string& filename, vector<stu>& v)
{
    ifstream in(filename);

    if (!in.is_open())
    {
        cout << "fail to open the file to read\n";
        return;
    }

    string firstline;
    getline(in, firstline);
    stu p;
    while (in >> p)
    {
        v.push_back(p);
    }

    in.close();
}

#include"stu.hpp"
#include"process.hpp"
#include<iostream>
#include<string>
#include<vector>
#include<algorithm>

int main()
{

    vector<stu> v;
    load("data5.txt", v);
    sort(v.begin(), v.end(), compare);

    output(cout, v);
    save("ans.txt", v);

    system("pause");
    return 0;
}