C++ Premier Plus 6th edition - Programming excercise - Chapter18 - 1

#include<iostream>
#include<initializer_list>
#include<algorithm>

using namespace std;

// create a template function, which will add all elements together
// initializer_list is container
template<typename T>
T average_list(initializer_list<T> il)
{
    T tot = 0;// sum of elements in initializer_list
    T ct = 0;// count of elements in initializer_list
    for (auto iter = il.begin(); iter != il.end(); iter++)
    {
        tot += *iter;
        ct++;
    }
	// another approach
    //for_each(il.begin(), il.end(), [&](T x) ->T {ct++; return tot += x; });// add each element to tot
    return tot / ct;
}

int main()
{
    // list of double deduced from list contents
    auto q = average_list({ 15.4, 10.7, 9.0 });
    cout << q << endl;
    // list of int deduced from list contents
    cout << average_list({ 20, 30, 19, 17, 45, 38 }) << endl;
    // forced list of double
    auto ad = average_list<double>({ 'A', 70, 65.33 });
    cout << ad << endl;
    cin.get();
    return 0;
}