#include <iostream>

#include <vector>

#include <algorithm>

using std::cout;

using std::endl;

using std::vector;

// https://changkun.de/modern-cpp/book/02-usability/index.html#decltype

void main00_decltype()

{

cout << endl

<< "# main00_decltype" << endl;

double x0 = 1;

int x1 = 2;

decltype(x0 + x1) x2;

cout << "do NOT depend on typeid() which is not c++ stardard" << endl;

cout << "double type is: " << typeid(x0).name() << endl;

cout << "int type is: " << typeid(x1).name() << endl;

cout << "int + double type is: " << typeid(x2).name() << endl;

cout << endl;

cout << "std::is_same<decltype(x0), double>::value: " << std::is_same<decltype(x0), double>::value << endl;

cout << "std::is_same<decltype(x0), decltype(x1)>::value: " << std::is_same<decltype(x0), decltype(x1)>::value << endl;

}

// https://changkun.de/modern-cpp/book/02-usability/index.html#%E5%B0%BE%E8%BF%94%E5%9B%9E%E7%B1%BB%E5%9E%8B%E6%8E%A8%E5%AF%BC

template <typename T0, typename T1>

auto main01_hf0(T0 x, T1 y)

{

return x + y;

}

void main01_typeDerivation()

{

cout << endl

<< "# main01_typeDerivation" << endl;

auto x0 = main01_hf0(233, 2.33);

if (std::is_same<decltype(x0), double>::value)

{

cout << "auto main01_hf0(int, double) return double value" << endl;

}

}

// https://changkun.de/modern-cpp/book/02-usability/index.html#%E5%8C%BA%E9%97%B4-for-%E8%BF%AD%E4%BB%A3

void main02_foreach()

{

cout << endl

<< "# main02_foreach" << endl;

vector<int> z0{1, 2, 3, 4};

if (auto itr0 = std::find(z0.begin(), z0.end(), 3); itr0 != z0.end())

{

*itr0 = 4;

}

for (auto x : z0)

{

cout << x << endl;

}

for (auto &x : z0)

{

x += 1;

}

for (auto x : z0)

{

cout << x << endl;

}

}

int main()

{

main00_decltype();

main01_typeDerivation();

main02_foreach();

return 0;

}