// Copyright (c) 2020 by Chrono

//

// g++ lambda.cpp -std=c++14 -o a.out;./a.out

// g++ lambda.cpp -std=c++14 -I../common -o a.out;./a.out

#include <iostream>

#include <string>

#include <vector>

#include <algorithm>

#include <functional>

using namespace std;

void my_square(int x)

{

cout << x*x << endl;

}

void case1()

{

auto pfunc = &my_square;

(*pfunc)(3);

auto func = [](int x)

{

cout << x*x << endl;

};

func(3);

}

void case2()

{

int n = 10;

auto func = [=](int x)

{

cout << x*n << endl;

};

func(3);

}

void case3()

{

auto f1 = [](){};

auto f2 = []()

{

cout << "lambda f2" << endl;

auto f3 = [](int x)

{

return x*x;

};// lambda f3

cout << f3(10) << endl;

}; // lambda f2

f1();

f2();

//f1 = f2;

vector<int> v = {3, 1, 8, 5, 0};

cout << *find_if(begin(v), end(v),

[](int x)

{

return x >= 5;

}

)

<< endl;

}

void case4()

{

int x = 33;

auto f1 = [=]()

{

//x += 10;

cout << x << endl;

};

auto f2 = [&]()

{

x += 10;

};

auto f3 = [=, &x]()

{

x += 20;

};

f1();

f2();

cout << x << endl;

f3();

cout << x << endl;

}

class DemoLambda final

{

public:

DemoLambda() = default;

~DemoLambda() = default;

private:

int x = 0;

public:

auto print()

{

//auto f = [=]()

return [this]()

{

cout << "member = " << x << endl;

};

}

};

void case5()

{

DemoLambda obj;

auto f = obj.print();

f();

}

void case6()

{

auto f = [](const auto& x)

{

return x + x;

};

cout << f(3) << endl;

cout << f(0.618) << endl;

string str = "matrix";

cout << f(str) << endl;

}

int main()

{

case1();

case2();

case3();

case4();

case5();

case6();

cout << "lambda demo" << endl;

}