#include <iostream>
#include <string>
#include <deque>
#include <list>

using namespace std;

template <typename T>
bool compareLT(const T &v1, const T &v2)
{
    return (v1 < v2);
}

float a = 13.3, b = 38.2;
string c = "Hello", d = "Goodbye";

cout << a << " < " << b << " = " << std::boolalpha << compareLT(a, b) << endl;
cout << c << " < " << d << " = " << std::boolalpha << compareLT(c, d) << endl;

template <class T>
class foo
{
private:
    T a;
    bool isDefault = true;

public:
    foo(){};
    foo(T v)
    {
        a = v;
        isDefault = false;
    }
    T getFoo();
    void setFoo(T v)
    {
        a = v;
        isDefault = false;
    }
};

template <class T>
T foo<T>::getFoo()
{
    if (isDefault) {
        cerr << "Error value was not set" << endl;
    }
    return a;
} // End of getFoo

foo<int> x;
foo<string> y("Hello");
foo<float> z;

x.setFoo(8);

cout << "X is " << x.getFoo() << endl;
cout << "Y is " << y.getFoo() << endl;
cout << "Z is " << z.getFoo() << endl;

template <class T>
class mypair
{
    T a, b;

public:
    mypair(T first, T second)
    {
        a = first;
        b = second;
    }
    T getmax();
};

template <class T>
T mypair<T>::getmax()
{
    T retval;
    retval = a > b ? a : b;
    return retval;
}

mypair<int> myint(100, 75);
cout << "Max is " << myint.getmax() << endl;

mypair<string> mystring("fish", "zebra");
cout << "Max is " << mystring.getmax() << endl;

template<class T>
constexpr T pi = T(3.1415926535897932385L); // variable template

template<class T>
T circular_area(T r) // function template
{
    return pi<T> * r * r; // pi<T> is a variable template instantiation
}

float r1 = 3.2;
circular_area(r1)

double r2 = 3.2;
circular_area(r2)

int r3 = 3;
circular_area(r3)

pi<int>

template <typename FUNC>
void do_n_times(FUNC fn, int n) {
    for(int i=0; i<n; ++i) fn();
}

void printHello() {
    cout << "Hello!" << endl;
}

do_n_times(printHello, 10)

bool isOdd(int i) // true if odd, false if even
{ 
    return ((i % 2) == 1); 
} 

vector <int> li{0,1,2,3,4,5};
cout << *(find_if(li.begin(), li.end(), isOdd));

// What is the * for?
find_if(li.begin(), li.end(), isOdd)

// what if li were empty?
vector<int> li2;
find_if(li2.begin(), li2.end(), isOdd) // don't derefence this!

li2.end() == find_if(li2.begin(), li2.end(), isOdd) // don't derefence this!

vector<int> li3{2,4,6,8};
li3.end() == find_if(li3.begin(), li3.end(), isOdd) // don't derefence this!

do_n_times([] () { cout << "Hello!" << endl; }, 3)

int i = 0;
do_n_times([i] () { cout << "Hello! " << i << endl; }, 3)

int i = 0;
do_n_times([i] () { cout << "Hello! " << i++ << endl; }, 3)

int i = 0;
do_n_times([&i] () { cout << "Hello! " << i++ << endl; }, 3)

i

vector<int> li4{2,4,6,8,9};
find_if(li4.begin(), li4.end(), [] (int j) { return j % 2 == 1; })

*find_if(li4.begin(), li4.end(), [] () { return true; })

deque<int> mydeque(2, 100);
// deque <int>::iterator it; // but use auto 
mydeque.push_front(200);
mydeque.push_front(300);
cout << "mydeque contains: ";
for(auto it3 = mydeque.begin(); it3 != mydeque.end(); ++it3)
    cout << ' ' << *it3;
cout << '\n';

std::list <int> mylist;
for(int i = 1; i <= 5; ++i)
    mylist.push_back(i); // 1 2 3 4 5 
auto it = mylist.begin(); // std::list <int>::iterator
++it; 
mylist.insert(it, 10);
mylist.insert(it, 2, 20);
--it;
std::vector <int> myvector(2, 30);
mylist.insert(it, myvector.begin(), myvector.end());
std::cout << "mylist contains: ";
for(it = mylist.begin(); it != mylist.end(); ++it)
    std::cout << ' ' << *it;
std::cout << '\n';

string s = "Hello", s2 = ", World", s3 = ", DeKalb";

s.size()

s + s2

s2 == s3

s2 = s3;
s + s2