//本博主所写的代码仅为阅读者提供参考；
//若有不足之处请提出，博主会尽所能修改；
//附上课后编程练习题目；
//若是对您有用的话请点赞或分享提供给它人
//18.12 - 1.cpp
#include <iostream>
#include <initializer_list>
template <typename T>
T average_list(std::initializer_list<T> arr)
{
T sum = 0;
int num = 0;
for (auto x = arr.begin(); x != arr.end(); ++x, ++num)
{
sum += *x;
}
return sum / num;
}
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;
}
//---------------------------------------------------------------------------------------------------------
//18.12 - 2.cpp
#include <iostream>
#include <string>
#include <utility>
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()
{
cout << "Default constructor called.\n";
pi = new Info;
pi->qcode = "none";
pi->zcode = "none";
}
Cpmv::Cpmv(string q, string z)
{
cout << "String constructor called.\n";
pi = new Info;
pi->qcode = q;
pi->zcode = z;
}
Cpmv::Cpmv(const Cpmv &cp)
{
cout << "Copy constructor called.\n";
pi = new Info;
pi->qcode = cp.pi->qcode;
pi->zcode = cp.pi->zcode;
}
Cpmv::Cpmv(Cpmv &&mv)
{
cout << "Move constructor called.\n";
pi = mv.pi; //地址直接覆盖;
mv.pi = nullptr;
}
Cpmv::~Cpmv()
{
delete pi;
}
Cpmv &Cpmv::operator=(const Cpmv &cp)
{
if (this != &cp)
{
delete pi;
pi = new Info;
pi->qcode = cp.pi->qcode;
pi->zcode = cp.pi->zcode;
}
return *this;
cout << "Copy assignment operator called.\n";
}
Cpmv &Cpmv::operator=(Cpmv &&mv)
{
if (this != &mv)
{
delete pi;
pi = mv.pi; //地址直接覆盖;
mv.pi = nullptr;
}
return *this;
cout << "Move assignment operator called.\n";
}
Cpmv Cpmv::operator+(const Cpmv &obj) const
{
return Cpmv(pi->qcode + obj.pi->qcode, pi->zcode + obj.pi->zcode);
}
void Cpmv::Display() const
{
if (pi != nullptr)
{
cout << "The qcode is " << pi->qcode << endl;
cout << "The zcode is " << pi->zcode << endl;
}
else
{
cout << "Cpmv::pi pointer is nullptr" << endl;
}
cout << endl;
return;
}
int main()
{
Cpmv temp1;
cout << "temp1:\n";
temp1.Display();
Cpmv temp2("black", "clover");
cout << "temp2:\n";
temp2.Display();
Cpmv temp3(temp1);
cout << "temp3:\n";
temp3.Display();
cout << "temp4 = temp1:\n";
Cpmv temp4;
temp4 = temp1;
cout << "temp4:\n";
temp4.Display();
cout << "temp1:\n";
temp1.Display();
cout << "temp5 = move(temp2):\n";
Cpmv temp5;
temp5 = move(temp2);
cout << "temp5:\n";
temp5.Display();
cout << "temp2:\n";
temp2.Display();
cout << "temp6 = temp3 + temp4:\n";
Cpmv temp6 = temp3 + temp4;
cout << "temp6:\n";
temp6.Display();
return 0;
}
//---------------------------------------------------------------------------------------------------------
//18.12 - 3.cpp
#include <iostream>
using namespace std;
long double sum_value()
{
return 0;
}
template <typename T>
long double sum_value(const T &value)
{
return value;
}
template <typename T, typename... Args>
long double sum_value(const T &value, const Args &...args)
{
return value + sum_value(args...);
}
int main()
{
int n = 14;
double x = 2.71828;
long y = 100000;
char ch = 'x';
cout << sum_value(n, x, y, ch, 'K', 66, 33.67);
return 0;
}
//---------------------------------------------------------------------------------------------------------
//18.12 - 4.cpp
/*应该是书上的程序清单中的16.15, 题目有误在此纠正*/
#include <iostream>
#include <list>
#include <algorithm>
using namespace std;
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);
auto lambda_outint = [](int n)
{ cout << n << " "; };
cout << "Original lists:\n";
for_each(yadayada.begin(), yadayada.end(), lambda_outint);
cout << endl;
for_each(etcetera.begin(), etcetera.end(), lambda_outint);
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(), lambda_outint);
cout << endl;
for_each(etcetera.begin(), etcetera.end(), lambda_outint);
cout << endl;
return 0;
}
//-----------------------------------------------------------------
//------------------------------------------2021年8月6日 ----------------------------------------------
