Explain C++ code

Question

Can I get some help with explanation of the following code?

#include 

class Vector {
    private:
        double∗ elem; // pointer to the el         


        

Answer 1

Vector(int s) defines a constructor - a special method that is called when object is created.

:elem{new double[s]}, sz{s} is a initializer list - it initializes object's fields. The whole part:

Vector(int s):elem{new double[s]}, sz{s} {}

Works same as

Vector(int s) {    
elem = new double[s];
sz = s;
}

However, initializer lists can be used to initialize constants and references.