(C++기초플러스 6판 프로그래밍 연습 정답,솔루션) CHAPTER 18 새로운 C++ 표준과의 만남 p.1540~ 1번~4번

1번

#include<iostream>
#include <initializer_list>

template<typename T>
T average_list(std::initializer_list<T> il)
{
	T sum = 0;
	for (auto it=il.begin(); it!=il.end(); it++)
		sum += *it;
	return sum / il.size();
}


int main()
{
	using namespace std;

	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;

}

 

 

2번

#include<iostream>
#include <string>
#include <utility>

class Cpmv
{
public:
	struct Info
	{
		std::string qcode;
		std::string zcode;
	};
private:
	Info* pi;
public:
	Cpmv();
	Cpmv(std::string q, std::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(nullptr)
{
}

Cpmv::Cpmv(std::string q, std::string z)
	: pi(new Info)
{
	pi->qcode = q;
	pi->zcode = z;
}

Cpmv::Cpmv(const Cpmv& cp)
{
	pi->qcode = cp.pi->qcode;
	pi->zcode = cp.pi->zcode;
}

Cpmv::Cpmv(Cpmv&& mv)
	:pi(mv.pi)
{
	std::cout << "이동 생성자 생성 && :\n";
	mv.pi = nullptr;
}

Cpmv::~Cpmv()
{
	if (pi) delete pi;
	pi = nullptr;
}

Cpmv& Cpmv::operator=(const Cpmv& cp)
{

	if (pi) delete pi;
	pi = cp.pi;
	return *this;
}

Cpmv& Cpmv::operator=(Cpmv&& mv)
{
	std::cout << "이동 생성자 생성 = :\n";
	pi = mv.pi;
	mv.pi = nullptr;
	return *this;
}

Cpmv Cpmv::operator+(const Cpmv& obj) const
{
	std::string qcode;
	std::string zcode;
	if (pi) {
		qcode += pi->qcode;
		zcode += pi->zcode;
	}
	if (obj.pi) {
		qcode += obj.pi->qcode;
		zcode += obj.pi->zcode;
	}
	Cpmv temp(qcode, zcode);
	return temp;
}

void Cpmv::Display() const
{
	std::cout << "qcode: " << pi->qcode << " \t"
		<< ", zcode: " << pi->zcode << '\n';
}


int main()
{
	Cpmv one("q1", "z1");
	std::cout << "one -> "; one.Display();

	Cpmv two("q2", "z2");
	std::cout << "two -> "; two.Display();

	Cpmv three(Cpmv("q3", "z3"));
	std::cout << "three -> "; three.Display();

	Cpmv four;
	four = one + two + three;
	std::cout << "four -> "; four.Display();
	return 0;
}

 

 

3번

#include<iostream>
long double sum_values() { return 0; }

template<typename T,typename...Args>
long double sum_values(T value, Args...args)
{
	long double sum = 0;
	return value + sum_values(args...);
}

int main()
{
	long double test;
	test = sum_values(1.4, 2.5, 3.4, 'a');
	std::cout << test << '\n';
	return 0;
}

 

 

4번

// functor.cpp -- 펑크터를 사용한다
#include <iostream>
#include <list>
#include <iterator>
#include <algorithm>

int main()
{
    using std::list;
    using std::cout;
    using std::endl;

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


    int vals[10] = { 50, 100, 90, 180, 60, 210, 415, 88, 188, 201 };
    list<int> yadayada(vals, vals + 10); // range 생성자
    list<int> etcetera(vals, vals + 10);

    // C++11은 다음의 코드를 대신 사용할 수 있다
    // list<int> yadayada = {50, 100, 90, 180, 60, 210, 415, 88, 188, 201};
    // list<int> etcetera {50, 100, 90, 180, 60, 210, 415, 88, 188, 201};

    cout << "원래의 리스트:\n";
    for_each(yadayada.begin(), yadayada.end(), outint);
    cout << endl;
    for_each(etcetera.begin(), etcetera.end(), outint);
    cout << endl;
    yadayada.remove_if([](int n) {return n > 100; });               // 이름이 있는 함수 객체를 사용한다
    etcetera.remove_if([](int n) {return n > 200; });   // 함수 객체를 생성한다
    cout << "정비된 리스트:\n";
    for_each(yadayada.begin(), yadayada.end(), outint);
    cout << endl;
    for_each(etcetera.begin(), etcetera.end(), outint);
    cout << endl;
    return 0;
}