实验6

Vector.hpp

#include <iostream>
#include <stdexcept>

using namespace std;

template<typename T>
class Vector 
{
    private:
        int length;
        T *space;
        
    public:
        Vector<T>(int l, T value=0): length{l} {
            if(l<0)
                throw length_error("Vector constructor: negative size");
            space = new T[l];
            for(int i=0; i<l; i++)
                space[i] = value;
        }
        Vector<T>(const Vector<T>& x){
            length = x.length;
            space = new T[length];
            for(int i=0; i<x.length; i++)
                space[i] = x.space[i];
        }
        ~Vector<T>() {    delete[] space;    }
        
        int get_size(){    return length;    }
        T& at(int i){
            if(i>=length || i<0)
                throw out_of_range("Vector: index out of range");
            return space[i];
        }
        T& operator[](int i){
            if(i>=length || i<0)
                throw out_of_range("Vector: index out of range");
            return space[i];
        }
        
        friend void output(const Vector<T> x){
            for(int i=0; i<x.length; i++)
            {
                cout << x.space[i];
                if(i!=x.length-1)
                    cout <<", ";
            }
            cout<<endl;
        }
};

test4.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();
}

Student.hpp

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

using namespace std;

class Student
{
    private:
        string ID;
        string Name;
        string Major;
        int Score;
        
    public:
        Student() = default;
        ~Student() = default;
        
        string Get_Major()    const { return Major; }
        int Get_Score() const { return Score; }
        
        friend ostream& operator<<( ostream &out, const Student &v ){
            out << left << setw(15) << v.ID
                        << setw(15) << v.Name
                        << setw(15) << v.Major
                        << setw(15) << v.Score;
            return out;
        }
        friend istream& operator>>( istream &in, Student &v ){
            in >> v.ID >> v.Name >> v.Major >> v.Score;
            return in;
        }
};

bool Stucmp(const Student a, const Student 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<Student> &v )
{
    for(auto &i: v)
        out << i << endl;
}
void WriFil(const string &filename, vector<Student> &v){    
    ofstream out(filename);
    if(!out.is_open())
    {  cout<<"fail to open"<<endl;    return;  }
    
    output(out,v);
    out.close();
}
void ReadFil(const string &filename, vector<Student> &v){
    ifstream in(filename);
    if(!in.is_open())
    {  cout<<"fail to open"<<endl;    return;  }
    
    string title;
    getline(in, title);
    
    Student t;
    while( in >> t )
        v.push_back(t);
    in.close();
} 

tast5.cpp

#include <iostream>
#include <vector>
#include <algorithm>
#include "Student.hpp"

using namespace std;

int main()
{
    vector<Student> v;
    
    ReadFil("data5.txt",v);
    sort( v.begin(), v.end(), Stucmp);
    output(cout,v);
    WriFil("ans5.txt",v);
    
    return 0;
}