实验6 模板类、文件I/O和异常处理

任务4：

Vector.hpp

#include<bits/stdc++.h>
using namespace std;
template <typename T>
class Vector{
    public:
        Vector(int size,int value=0):size{size}{
            if(size<0) throw length_error("negative size");
            else{
                ptr=new T[size];
                for(int i=0;i<size;i++){
                    ptr[i]=value;
                }
            }
        }
        int get_size() const{
            return size;
        }
        T& at(int val){
            if(val>=size) throw out_of_range("index out of range");
            else  return ptr[val];
        }
        T& operator[] (int val){
            if(val<0||val>=size)  throw out_of_range("index out of range");
            else return ptr[val];
        }
        friend void output(const Vector<T> &x){
            for(int i=0;i<x.get_size();i++){
                cout<<x.ptr[i]<<", ";
            }
            cout<<endl;
        }
        Vector(const Vector<T>& x):size(x.size),ptr(new T[size]){
            for(int i=0;i<size;i++){
                ptr[i]=x.ptr[i];
            }
        }
    private:
        int size;
        T* ptr;
};

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：

 

任务5：

task5.cpp

#include<bits/stdc++.h>
using namespace std;
class student{
    private:
        string name;
        string number;
        int grade;
        string major;
    public:
        student()=default;
        ~student()=default;
        string get_major() const{
            return major;
        }
        int get_grade() const{
            return grade;
            
        }
        friend ostream& operator<<(ostream &out,const student &s){
            out<<setiosflags(ios_base::left);
            out<<setw(15)<<s.number<<setw(15)<<s.name<<setw(15)<<s.major<<setw(15)<<s.grade;
            return out;
        }
        friend istream &operator>>(istream &in,student &s){
            in>>s.number>>s.name>>s.major>>s.grade;
            return in;
        }
};

void ld(const string &filename,vector<student> &s){
    ifstream in(filename);
    if(!in.is_open())
    {
      cout<<"file open read\n";
      return ;
    }
      string title_line;
      getline(in,title_line);
      student t;
      while(in>>t)
        s.push_back(t);
      in.close();
}

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

void ew(const string &filename,vector<student> &s){
    ofstream out(filename);
    if(!out.is_open()){
        cout<<"file open write\n";
        return ;
        
    }
    output(out,s);
    out.close();
}


bool compare(student &s1,student &s2){
    if(s1.get_major()<s2.get_major())  return true;
    if(s1.get_major()==s2.get_major())  return s1.get_grade()>s2.get_grade();
    return false;
}
int main(){
    vector<student> s;
    ld("data5.txt",s);
    sort(s.begin(),s.end(),compare);
    output(cout,s);
    ew("data5_2.txt",s);
}
 

运行结果截图：

实验总结：通过这次实验，加深了对模板类使用的理解。