实验6 C++

任务四：

Vector.hpp

#pragma once
#include <iostream> 
#include <stdexcept>using namespace std;template <typename T>
class Vector {
public:Vector(int n, int p = 0);Vector(const Vector<T> &v);~Vector();int get_size() const;T& at(int i);T& operator[](int i);
private:int size;T *a;template <typename T1>friend void output(const Vector<T1> &v);
};
template <typename T>
Vector<T>::Vector(int n, int p) : size{n} {if(n < 0)throw length_error("Vector constructor: negative size");else {a = new T [n];for(int i = 0; i < n; i++)a[i] = p; }
}template <typename T>
Vector<T>::Vector(const Vector<T> &v) {size = v.size;a = new T [size];for(int i = 0; i < size; i++)a[i] = v.a[i];
}template <typename T>
Vector<T>::~Vector() {delete [] a;
}template <typename T>
int Vector<T>::get_size() const {return size;}template < typename T> 
T& Vector<T>::at(int i) {if(i >= size || i < 0)throw invalid_argument("Vector: index out of range");elsereturn a[i];
}template <typename T> 
T& Vector<T>::operator[](int i) {if(i >= size || i < 0)throw invalid_argument("Vctor: index out of range");elsereturn a[i];
}template <typename T1>
void output(const Vector<T1> &v) 
{for(int i = 0; i < v.size - 1; i++)cout << v.a[i] << ", ";cout << v.a[v.size - 1] << endl;
}

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：

任务五：

task5.cpp

 #include <iostream>
#include <iomanip>
#include <string>
#include <vector>
#include <fstream>
#include <algorithm>using namespace std;class Stu {
public:Stu() = default;~Stu() = default;string get_major() const {return major;}int get_score() const {return score;}friend ostream& operator<<(ostream &out, const Stu &s);friend istream& operator>>(istream &in, Stu &s);private:string no;string name;string major;int score;   
};
ostream& operator<<(ostream &out, const Stu &s) {out << setiosflags(ios_base::left);out << setw(10) << s.no<< setw(10) << s.name<< setw(10) << s.major<< setw(10) << s.score << endl;return out;
}istream& operator>>(istream &in, Stu &s) {in >> s.no >> s.name >> s.major >> s.score;return in;
}bool cmp(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> &v) {for(auto &i : v)out << i ;
}void load(const string &filename, vector<Stu> &v) {ifstream in(filename);if(!in.is_open()) {cout << "fail to open file to read" << endl;return;                   }string title_line;getline(in, title_line);Stu s;while(in >> s)v.push_back(s);in.close();
}void save(const string &filename, vector<Stu> &v) {ofstream out(filename);if(!out.is_open()) {cout << "fail to open file to write" << endl;return;}output(out, v);out.close();
}int main() {vector<Stu> v;load("data5.txt", v);sort(v.begin(), v.end(), cmp);output(cout, v);save("ans5.txt", v);
}

运行结果：