Vector v1 = {1,2,3,4,5}; // v1 has 5 elements
Vector v2 = {1.23, 3.45, 6.7, 8}; // v2 has 4 elements
Vector’s initializer-list constructor might be defined like this:
Vector::Vector(std::initializ er_list<double> lst) // initialize with a list
     :elem{new double[lst.siz e()]}, sz{lst.siz e()}
{
     copy(lst.begin(),lst.end(),elem); // copy from lst into elem
}