cpp/CPPlusV6/Chapter 16/ilist.cpp

// ilist.cpp  -- use initializer_list
#include <iostream>
#include <initializer_list>

double sum(std::initializer_list<double> il);
double average(const std::initializer_list<double> & ril);

int main()
{
    using std::cout;

    cout << "List 1: sum = " << sum({2,3,4})
         <<", ave = " << average({2,3,4}) << '\n';
    std::initializer_list<double> dl = {1.1, 2.2, 3.3, 4.4, 5.5};
    cout << "List 2: sum = " << sum(dl)
         <<", ave = " << average(dl) << '\n';
    dl = {16.0, 25.0, 36.0, 40.0, 64.0};
    cout << "List 3: sum = " << sum(dl)
         <<", ave = " << average(dl) << '\n';
    // std::cin.get();
    return 0;
}

double sum(std::initializer_list<double> il)
{
    double tot = 0;
    for (auto p = il.begin(); p !=il.end(); p++)
        tot += *p;
    return tot;
}

double average(const std::initializer_list<double> & ril)
{
    double tot = 0;
    int n = ril.size();
    double ave = 0.0;
    
    if (n > 0)
    {
        for (auto p = ril.begin(); p !=ril.end(); p++)
            tot += *p;
        ave = tot / n;
    }
    return ave;
}