实验6 模板类、文件I/O和异常处理

1.实验任务1

运行代码：

Complex.h:

#pragma once

#include <iostream>
#include <stdexcept>

// 声明
////////////////////////////////////////////////////
// 复数模板类声明
template<typename T>
class Complex {
public:
    Complex(T r = 0, T i = 0);
    Complex(const Complex<T>& c);

    T get_real() const;
    T get_imag() const;

    // 重载+=为成员函数
    Complex<T>& operator+=(const Complex<T>& c);

    // 重载<<、>>为友元函数
    template<typename T1>
    friend std::ostream& operator<<(std::ostream& out, const Complex<T1>& c);

    template<typename T1>
    friend std::istream& operator>>(std::istream& in, Complex<T1>& c);

private:
    T real, imag;
};

// 普通函数声明
// 重载+用于Complex类型
template<typename T>
Complex<T> operator+(const Complex<T>& c1, const Complex<T>& c2);

// 重载==用于Complex类型
template<typename T>
bool operator==(const Complex<T>& c1, const Complex<T>& c2);


// 实现
////////////////////////////////////////////////////
// 成员函数模板实现
template<typename T>
Complex<T>::Complex(T r, T i) : real{ r }, imag{ i } {
}

template<typename T>
Complex<T>::Complex(const Complex<T>& c) : real{ c.real }, imag{ c.imag } {
}

template<typename T>
T Complex<T>::get_real() const {
    return real;
}

template<typename T>
T Complex<T>::get_imag() const {
    return imag;
}

// 重载+=为成员函数
template<typename T>
Complex<T>& Complex<T>::operator+=(const Complex<T>& c) {
    real += c.real;
    imag += c.imag;

    return *this;
}

///////////////////////////////////////
// 友元函数模板实现
template<typename T1>
std::ostream& operator<<(std::ostream& out, const Complex<T1>& c) {
    if (c.imag >= 0)
        out << c.real << " + " << c.imag << "i";
    else
        out << c.real << " - " << -c.imag << "i";

    return out;
}

template<typename T1>
std::istream& operator>>(std::istream& in, Complex<T1>& c) {
    in >> c.real >> c.imag;

    return in;
}

///////////////////////////////////////
// 普通函数模板实现
// 重载+用于Complex类型
template<typename T>
Complex<T> operator+(const Complex<T>& c1, const Complex<T>& c2) {
    return Complex<T>(c1.get_real() + c2.get_real(),
        c1.get_imag() + c2.get_imag());
}

// 重载==用于Complex类型
template<typename T>
bool operator==(const Complex<T>& c1, const Complex<T>& c2) {
    return c1.get_real() == c2.get_real() &&
        c1.get_imag() && c2.get_imag();
}

task1.cpp:

#include "Complex.hpp"
#include <iostream>
#include <fstream>
#include <stdexcept>

void test1();
void test2();

int main() {
    using namespace std;

    cout << "测试1: 复数模板类测试" << endl;
    test1();

    cout << "\n测试2: 文件I/O测试" << endl;
    test2();
}

void test1() {
    using namespace std;

    Complex<double> c1{ 3.5, 2 }, c2;
    cout << "Enter c2: ";
    cin >> c2;
    cout << "c1 = " << c1 << endl;
    cout << "c2 = " << c2 << endl;
    cout << "c1 == c2: " << boolalpha << (c1 == c2) << endl;

    cout << "c1 + c2 = " << c1 + c2 << endl;
    c1 += c2;
    cout << "c1.real = " << c1.get_real() << endl;
    cout << "c1.imag = " << c1.get_imag() << endl;

    cout << "c1 == c2: " << boolalpha << (c1 == c2) << endl;
}

void test2() {
    using namespace std;

    Complex<int> c1{ 1, 2 }, c2{ 9, -7 };
    ofstream out("ans.txt");
    if (!out.is_open()) {
        cout << "fail to open file ans.txt to write\n";
        return;
    }

    out << "c1 = " << c1 << endl;
    out << "c2 = " << c2 << endl;
    out << "c1 + c2 = " << c1 + c2 << endl;
    out << "(c1 == c2) = " << boolalpha << (c1 == c2) << endl;

    out.close();
    cout << "测试ok!" << endl;
}

运行截图：

 

2.实验任务2

运行代码：

Contestant.hpp:

#pragma once

#include <iostream>
#include <iomanip>
#include <string>

using std::string;
using std::ostream;
using std::istream;
using std::setw;
using std::setprecision;
using std::setiosflags;
using std::ios_base;

// Contestant类声明
class Contestant {
public:
    Contestant() = default;
    ~Contestant() = default;

    int get_num() const { return num; }
    float get_time_usage() const { return time_usage; }

    friend ostream& operator<<(ostream& out, const Contestant& c);
    friend istream& operator>>(istream& in, Contestant& c);

private:
    string no;          // 学号
    string name;        // 姓名
    string major;       // 专业
    int num;            // 解题数
    float time_usage;   // 总用时
};

// 友元函数实现
// 重载流插入运算符<<
ostream& operator<<(ostream& out, const Contestant& c) {
    out << setiosflags(ios_base::left);
    out << setw(15) << c.no
        << setw(15) << c.name
        << setw(15) << c.major
        << setw(5) << c.num
        << setprecision(2) << c.time_usage;

    return out;
}

// 重载流提取运算符>>
istream& operator>>(istream& in, Contestant& c) {
    in >> c.no >> c.name >> c.major >> c.num >> c.time_usage;

    return in;
}

utils.hpp:

#include "Contestant.hpp"
#include <fstream>
#include <iostream>
#include <string>
#include <vector>

// 排序函数
// 按解题数比较，解题数相同的情况下，按总用时比较，总用时越少，排名越靠前
bool compare_by_solutionInfo(const Contestant& c1, const Contestant& c2) {
    if (c1.get_num() > c2.get_num())
        return true;

    if (c1.get_num() == c2.get_num())
        return c1.get_time_usage() < c2.get_time_usage();

    return false;
}

// 把vector<Constestant>对象中的元素插入到输出流out
void output(std::ostream& out, const std::vector<Contestant>& v) {
    for (auto& i : v)
        out << i << std::endl;
}


// 把vector<Contestant>对象中的元素写到filename文件中
void save(const std::string& filename, std::vector<Contestant>& v) {
    using std::ofstream;

    ofstream out(filename);
    if (!out.is_open()) {
        std::cout << "fail to open file to write\n";
        return;
    }

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

// 从文件filename读取参赛选手信息到vector<Contestant>对象
void load(const std::string& filename, std::vector<Contestant>& v) {
    using std::ifstream;

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

    std::string title_line;
    getline(in, title_line);     // 跳过标题行

    int first_column;
    Contestant t;
    while (in >> first_column >> t)
        v.push_back(t);

    in.close();
}

task2.cpp:

#include "Contestant.hpp"
#include "utils.hpp"
#include <iostream>
#include <vector>
#include <algorithm>


void test() {
    using namespace std;

    vector<Contestant> v;

    load("data2.txt", v);   // 从文件加载选手信息到对象v
    sort(v.begin(), v.end(), compare_by_solutionInfo);  // 按解题情况排序
    output(cout, v);    // 输出对象v中信息到屏幕
    save("ans.txt", v); // 把对象v中选手信息保存到文件
}

int main() {
    test();
}

运行截图：

 

3.实验任务3

运行代码：

Triangle.hpp:

#include <iostream>
#include <stdexcept>
#include <cmath>

using namespace std;

class Triangle {
public:
    Triangle(double s1, double s2, double s3);
    ~Triangle() = default;

    double area() const;

private:
    double a, b, c;
};

Triangle::Triangle(double s1, double s2, double s3) : a{ s1 }, b{ s2 }, c{ s3 } {
    if (a <= 0 || b <= 0 || c <= 0)
        throw invalid_argument("边长出现负值");

    if (a + b <= c || b + c <= a || a + c <= b)
        throw invalid_argument("不满足任意两边之和大于第三边");
}

double Triangle::area() const {
    double s = (a + b + c) / 2;
    return sqrt(s * (s - a) * (s - b) * (s - c));
}

task3.cpp:

#include "Triangle.hpp"
#include <iostream>
#include <fstream>

void test() {
    using namespace std;

    cout << "从文件读入三角形三边边长，计算面积" << endl;

    ifstream in("data3.txt");
    if (!in.is_open()) {
        cout << "fail to open file to read\n";
        return;
    }

    double a, b, c;
    do {
        cout << "三角形边长: ";
        in >> a >> b >> c;
        cout << a << " " << b << " " << c << endl;

        try {
            Triangle t(a, b, c);
            cout << "三角形面积: " << t.area() << endl << endl;
        }
        catch (const exception& e) {
            cout << "error: " << e.what() << endl << endl;
        }

        if (in.peek() == EOF)
            break;
    } while (1);

    in.close();
}

int main() {
    test();
}

运行截图：

 

4.实验任务4

运行代码：

Vector.hpp:

#include <iostream>
#include <stdexcept>
using namespace std;
template <typename T>
class Vector {
private:
    T* data;
    int n;
public:
    Vector(int n, int element = 0) :n(n) {
        if (n < 0) {
            throw length_error("Vector constructor:negative size");
        }
        else {
            data = new T[n];
            for (int i = 0; i < n; i++) {
                data[i] = element;
            }
        }

    }
    Vector(const Vector<T>& x) :n(x.n), data{ new T[n] } {
        for (int i = 0; i < n; i++) {
            data[i] = x.data[i];
        }
    }
    int get_size()const {

        return n;
    }
    T& at(int i) {
        if (i < 0 || i >= n) {
            throw out_of_range("Vector:index out of range");
        }
        return data[i];
    }
    friend void output(const Vector<T>& x)
        {
            for (int i = 0; i < x.get_size(); i++) {
                if (i == x.get_size() - 1) {
                    cout << x.data[i];
                }
                else
                {
                    cout << x.data[i] << ",";
                }
            }
            cout << endl;
        }
    T& operator[](int i)const {
        if (i < 0 || i >= n) {
            throw out_of_range("Vector:index out of range");
        }
        return data[i];
    }
};

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();
}

 运行截图：

 

5.实验任务5

运行代码：

contestant.hpp:

#pragma once
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
class contestant {
private:
    string no;
    string name;
    string major;
    int grades;
public:
    contestant() = default;
    ~contestant() = default;
    string get_major() {
        return major;
    }
    int get_grades() {
        return grades;
    }
    friend ostream& operator<<(ostream& out, const contestant& c) {
        out << setiosflags(ios_base::left);
        out << setw(15) << c.no
            << setw(15) << c.name
            << setw(15) << c.major
            << setw(15) << c.grades;
        return out;
    }
    friend istream& operator>>(istream& in, contestant& c) {
        in >> c.no >> c.name >> c.major >> c.grades;
        return in;
    }
};

utils.hpp:

#include "contestant.hpp"
#include <fstream>
#include <iostream>
#include <string>
#include <vector>
using namespace std;
bool compared( contestant& c1,  contestant& c2) {
    if (c1.get_major() < c2.get_major()) {
        return true;
    }
    if (c1.get_major() == c2.get_major()) {
        return c1.get_grades() > c2.get_grades();
    }
    return false;
}
void output(ostream& out, const vector<contestant>& v) {
    for (auto& i : v) {
        out << i << endl;
    }
}
void save(const string& filename, vector<contestant>& v) {
    ofstream out(filename);
    if (!out.is_open()) {
        cout << "fail to open file to write\n";
        return;
    }
    output(out, v);
    out.close();
}
void load(const string& filename, vector<contestant>& v) {
    ifstream in(filename);
    if (!in.is_open()) {
        cout << "fail to open file to read\n";
        return;
    }
    string title_line;
    getline(in, title_line);
    contestant t;
    while (in>>t) {
        v.push_back(t);
    }
    in.close();
}

task5.cpp:

#include "contestant.hpp"
#include "utils.hpp"
#include <iostream>
#include <vector>
#include <algorithm>
int main() {
    vector<contestant>v;
    load("data5.txt", v);
    sort(v.begin(), v.end(), compared);
    output(cout, v);
    save("ans.txt", v);
    return 0;
}

 运行截图：

 注意：

在VS中运行时，要将data5的编码格式由utf-8改为ansi才可以在控制台上显示出内容,但这样改动，ans.txt文件上的内容出现乱码