实验六

任务4：

代码：

#pragma once
#include<iostream>
#include<stdexcept>
using namespace std;
template<typename T>
class Vector{
    public:
        Vector(int n,const T& value=T()):size(n){
            if(n<0)
            {
                throw length_error("大小是负数!");
            }
            else
            {
                x=new T[n];
                for(int i=0;i<n;i++)
                {
                    x[i]=value;
                }
            }
        }
        Vector(const Vector<T>& other):size(other.size){
            x=new T[size];
            for(int i=0;i<size;i++)
            {
                x[i]=other.x[i];
            }
        }
        ~Vector(){
            delete[] x;
         }
         
         
         int get_size() const{
             return size;
        }
        
        
        T& at(int index){
                if(index>=size)
            {
                throw out_of_range("下标访问越界!");
            }
            else
            return x[index];
        }
        const T& at(int index) const
        {
            if(index>=size)
            {
                throw out_of_range("下标访问越界!");
            }
            else
            return x[index];
        }
        
        
        T& operator[](int i){
            return at(i);
        }
        const T& operator[](int i)const{
            return at(i);
        }
        
        
        friend void output(const Vector<T>& a)
        {
            for(int i=0;i<a.size;i++)
            {
                cout<<a[i]<<" ";
            }
            cout<<endl; 
        }
    private:
        int size;
        T* x;
};

#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();
}

运行截图：

 任务5：

代码：

#include<iostream>
#include<fstream>
#include<string>
#include<vector>
#include<algorithm>
#include<iomanip>
using namespace std;
class information{
    private:
        int id;
        string name;
        string major;//专业
        int score; 
    public:
        information()=default;
        ~information()=default;
        friend ostream& operator<<(ostream& out,const information& a)
        {
            out<<setiosflags(ios_base::left);
            out<<setw(10)<<a.id
               <<setw(10)<<a.name
               <<setw(10)<<a.major
               <<setw(10)<<a.score;
              
          return out; 
        }
        friend istream& operator>>(istream& in,information& a)
        {
            in>>a.id >>a.name>>a.major>>a.score;
            return in; 
        }
        string get_major()const {return major;}
        int get_score() const{return score;}
        
};
bool compare(const information& a,const information& b)
{
    if(a.get_major()<b.get_major())
    return true;
    if(a.get_major()==b.get_major()){
        return a.get_score()>b.get_score();
    }
    return false;
}
void output(ostream& out,const vector<information>& v)
{
    for(const auto &i:v)
    {
        out<<i<<endl;
    }
}
void save(const string &filename,vector<information>& v)
{
    ofstream outfile(filename);
    if(!outfile.is_open())
    {
        cout<<"文件打开失败";
        return;
    }
    output(outfile,v);
    outfile.close();
}
void load(const string& filename,vector<information>& v)
{
    ifstream infile(filename);
    if(!infile.is_open())
    {
        cout<<"文件打开失败";
        return; 
    }
    string line;
    getline(infile,line);//跳过标题行
    information a;
    while(infile>>a)
    v.push_back(a);
    
    infile.close();
    
}


int main()
{
    vector<information> v;
    load("data.txt",v);
    sort(v.begin(),v.end(),compare);
    output(cout,v);
    save("data1.txt",v);
}

 

运行截图：