C++ Primer Plus 第六版第十八章课后编程练习答案

Dear 丶 2023-05-22 15:26 146阅读 0赞

play.cpp

#include <iostream>
    using namespace std;
    #include <initializer_list>
    
    template <typename T>
    T average_list(initializer_list<T> i)
    {
        T sum = 0;
        int num = 0;
        for(auto p = i.begin(); p != i.end(); p++, num++)
            sum += *p;
        return sum / num;
    }
    
    int main()
    {
        auto q = average_list({15.4, 10.7, 9.0});
        cout << q << endl;
        cout << average_list({20, 30, 19, 17, 45, 38}) << endl;
        auto ad = average_list<double >({'A', 70, 65.33});
        cout << ad << endl;
    
        return 0;
    }

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play.cpp

#include "stdafx.h"
    #include <iostream>
    #include <string>
     
    using namespace std;
    class Cpmv
    {
    public:
        struct Info
        {
            string qcode;
            string zcode;
        };
    private:
        Info *pi;
    public:
        Cpmv();
        Cpmv(string q, string z);
        Cpmv(const Cpmv & cp);
        Cpmv(Cpmv && mv);
        ~Cpmv();
        Cpmv & operator=(const Cpmv & cp);
        Cpmv & operator=(Cpmv && mv);
        Cpmv operator+(const Cpmv & obj) const;
        void Display() const;
    };
     
    Cpmv::Cpmv()
    {
        pi = new Info;
        pi->qcode = "qcode";
        pi->zcode = "zcode";
        cout << "Default constructor called.\n";
    }
     
    Cpmv::Cpmv(string q, string z)
    {
        pi = new Info;
        pi->qcode = q;
        pi->zcode = z;
        cout << "String constructor called.\n";
    }
     
    Cpmv::Cpmv(const Cpmv & cp)
    {
        pi = new Info;
        pi->qcode = cp.pi->qcode;
        pi->zcode = cp.pi->zcode;
        cout << "Copy constructor called.\n";
    }
     
    Cpmv::Cpmv(Cpmv && mv)
    {
        pi = new Info;
        pi->qcode = mv.pi->qcode;
        pi->zcode = mv.pi->zcode;
        mv.pi->qcode = "qcode";
        mv.pi->zcode = "zcode";
        cout << "Move constructor called.\n";
    }
     
    Cpmv::~Cpmv()
    {
        delete pi;
        cout << "Deconstructor called.\n";
    }
     
    Cpmv & Cpmv::operator=(const Cpmv & cp)
    {
        cout << "Copy assignment operator called.\n";
        if (this == &cp)
        {
            return *this;
        }
        delete pi;
        pi = new Info;
        pi->qcode = cp.pi->qcode;
        pi->zcode = cp.pi->zcode;
        return *this;
    }
     
    Cpmv & Cpmv::operator=(Cpmv && mv)
    {
        cout << "Move assignment operator called.\n";
        if (this == &mv)
        {
            return *this;
        }
        delete pi;
        pi = new Info;
        pi->qcode = mv.pi->qcode;
        pi->zcode = mv.pi->zcode;
        mv.pi->qcode = "qcode";
        mv.pi->zcode = "zcode";
        return *this;
    }
     
    Cpmv Cpmv::operator+(const Cpmv & obj) const
    {
        cout << "Plus operator called.\n";
        Cpmv sum;
        sum.pi->qcode = this->pi->qcode + obj.pi->qcode;
        sum.pi->zcode = this->pi->zcode + obj.pi->zcode;
        return sum;
    }
     
    void Cpmv::Display() const
    {
        cout << "The qcode is " << this->pi->qcode << endl;
        cout << "The zcode is " << this->pi->zcode << endl;
        cout << endl;
    }
     
     
     
    int main()
    {
        Cpmv temp;
        cout << "Object 0:\n";
        temp.Display();
     
        Cpmv temp1("number one", "number two");
        cout << "Object 1:\n";
        temp1.Display();
     
        Cpmv temp2(temp);
        cout << "Object 2:\n";
        temp2.Display();
     
        cout << "Object 3 = Object 1:\n";
        Cpmv temp3;
        temp3 = temp1;
        cout << "Object 3:\n";
        temp3.Display();
        cout << "Object 1:\n";
        temp1.Display();
     
        cout << "Object 4 = move(Obejct 2):\n";
        Cpmv temp4;
        temp4 = move(temp2);
        cout << "Object 4:\n";
        temp4.Display();
        cout << "Object 2:\n";
        temp2.Display();
     
        cout << "Obejct 5 = Object 3 + Obejct 4:\n";
        Cpmv temp5 = temp3 + temp4;
        cout << "Obejct 5:\n";
        temp5.Display();
     
     
        system("pause");
        return 0;
    }

#include <iostream>
    using namespace std;
    
    long double sum_value()
    {
        return 0;
    }
    
    template <typename T>
    long double sum_value(const T &t)
    {
        return t;
    }
    
    template <typename T, typename... Args>
    long double sum_value(const T &t, const Args&... args)
    {
        return t + sum_value(args...);
    }
    
    int main()
    {
        int n = 100;
        double m = 99.66;
        long y = 100000;
        char ch = 'x';
        cout << sum_value(n, m, y, ch, 'A', 77, 99.52);
    
        return 0;
    }

![20200419213956394.png][]

#include <iostream>
    using namespace std;
    #include <list>
    
    auto outline_lambda = [](int n){ cout << n << " ";};
    
    int main()
    {
        int vals[10] = {50, 100, 90, 180, 60, 210, 415, 88, 188, 201};
        list<int> yadayada(vals, vals + 10);
        list<int> etcetera(vals, vals + 10);
    
        cout << "Original lists:\n";
        for_each(yadayada.begin(), yadayada.end(), outline_lambda);
        cout << endl;
        for_each(etcetera.begin(), etcetera.end(), outline_lambda);
        cout << endl;
        yadayada.remove_if([](int n) { return n > 100;});
        etcetera.remove_if([](int n) { return n > 200;});
        cout << "Trimmed lists:\n";
        for_each(yadayada.begin(), yadayada.end(), outline_lambda);
        cout << endl;
        for_each(etcetera.begin(), etcetera.end(), outline_lambda);
        cout << endl;
    
        return 0;
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5OTM4NjY2_size_16_color_FFFFFF_t_70 1][]

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[20200419213956394.png]: /images/20230521/f9d7c9b8eaf34b07beee847f56371b13.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5OTM4NjY2_size_16_color_FFFFFF_t_70 1]: /images/20230521/8c7f48efc65c4b1dbd18e0023df42d7f.png