C++ primer plus(第6版)中文版编程练习答案第18章

1、

//init.cpp

#include

#include

using namespace std;

template

T average_list(initializer_listil);

int main()

{

auto q = average_list({ 15.4, 10.7, 9.0 });

cout<< q <

cout<

auto ad = average_list({ 'A', 70, 65.33 });

cout<< ad <

system("pause");

return 0;

}

template

T average_list(initializer_listil)

{

T sum = 0;

inti = 0;

for (auto p = il.begin(); p != il.end(); p++, i++)

sum += *p;

return sum / i;

}

2、

//cpmv.h

#ifndef CPMV_H_

#define CPMV_H_

#include

#include

using namespace std;

classCpmv

{

public:

struct Info

{

stringqcode; stringzcode;

};

private:

Info *pi;

public:

Cpmv();

Cpmv(string q, string z);

Cpmv(constCpmv&cp);

Cpmv(Cpmv&&mv);

~Cpmv();

Cpmv&operator=(constCpmv&cp);

Cpmv&operator=(Cpmv&&mv);

Cpmv operator+(constCpmv&obj)const;

void Display()const;

};

Cpmv::Cpmv()

{

pi = new Info;

pi->qcode = "Nothing";

pi->zcode = "Nothing";

cout<< "Default construct called: \n";

Display();

}

Cpmv::Cpmv(string q, string z)

{

pi = new Info;

cout<< "String construct called: \n";

pi->qcode = q;

pi->zcode = z;

Display();

}

Cpmv::Cpmv(constCpmv&cp)

{

pi = new Info;

cout<< "Copy construct called: \n";

pi->qcode = cp.pi->qcode;

pi->zcode = cp.pi->zcode;

Display();

}

Cpmv::Cpmv(Cpmv&&mv)

{

pi = new Info; cout<< "Move construct called: \n";

pi->qcode = mv.pi->qcode;

pi->zcode = mv.pi->zcode;

mv.pi->qcode = "Nothing";

mv.pi->zcode = "Nothing";

Display();

}

Cpmv::~Cpmv()

{

cout<< "Destruct called! \n";

delete pi;

}

Cpmv&Cpmv::operator=(constCpmv&cp)

{

cout<< "Copy assignment operator called: \n";

if (this == &cp)

return *this;

pi->qcode = cp.pi->qcode;

pi->zcode = cp.pi->zcode;

Display();

return *this;

}

Cpmv&Cpmv::operator=(Cpmv&&mv)

{

cout<< "Move assignment operator called: \n";

if (this == &mv)

return *this;

pi->qcode = mv.pi->qcode;

pi->zcode = mv.pi->zcode;

mv.pi->qcode = "Nothing";

mv.pi->zcode = "Nothing";

Display();

return *this;

}

CpmvCpmv::operator+(constCpmv&obj)const

{

cout<< "Plus assignment operator called! \n";

Cpmv temp;

temp.pi->qcode = pi->qcode + obj.pi->qcode;

temp.pi->zcode = pi->zcode + obj.pi->zcode;

return temp;

}

voidCpmv::Display()const

{ cout<< pi->qcode<< ", " << pi->zcode<

}

#endif

//useCpmv.cpp

#include "cpmv.h"

int main()

{

{

Cpmv zero, one("one", "one");

cout<< "object zero: ";

zero.Display();

cout<< "object one: ";

one.Display();

Cpmv two = one + one;

cout<< "object two: ";

two.Display();

Cpmv three, four;

cout<< "three = one\n";

three = one;

cout<< "now object three = ";

three.Display();

cout<< "and object one = ";

one.Display();

cout<< "four = one + two\n";

four = one + two;

cout<< "now object four = ";

four.Display();

cout<< "four = move(one)\n";

four = move(one);

cout<< "now object four = ";

four.Display();

cout<< "and object one = ";

one.Display();

system("pause");

return 0;

}

}

3、

//sum_value.cpp

#include

#include #include

using namespace std;

long double sum_value(){ return 0; }

template

long double sum_value(const T &value)

{

return value;

}

template

long double sum_value(const T &value, constArgs&... args)

{

return value + sum_value(args...);

}

int main()

{

int n = 14;

double x = 2.7;

long y = 2000;

charch = 'a';

cout<< "Sum of :" <

system("pause");

return 0;

}

4、

//functor.cpp

#include

#include

#include

#include

using namespace std;

autooutint = [](int n){cout<< n << " "; };

int main()

{

intvals[10] = { 50, 100, 90, 180, 60, 210, 415, 88, 188, 201 };

listyadayada(vals, vals + 10);

list etcetera(vals, vals + 10);