Initializer Lists

Initializer lists initialize member variables to specific values, just before the class constructor runs. This initialization ensures that class members are automatically initialized when an instance of the class is created.

Date::Date(int day, int month, int year) : year_(y) {
  Day(day);
  Month(month);
}

In this example, the member value year is initialized through the initializer list, while day and month are assigned from within the constructor. Assigning day and month allows us to apply the invariants set in the mutator.

In general, prefer initialization to assignment. Initialization sets the value as soon as the object exists, whereas assignment sets the value only after the object comes into being. This means that assignment creates and opportunity to accidentally use a variable before its value is set.

In fact, initialization lists ensure that member variables are initialized before the object is created. This is why class member variables can be declared const, but only if the member variable is initialized through an initialization list. Trying to initialize a const class member within the body of the constructor will not work.

Instructions

1. Declare class Person.
2. Add std::string name to class Person.
3. Create a constructor for class Person.
4. Add an initializer list to the constructor.
5. Create class object.