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How can a base class constructor be used as a derived class?
Base class constructors are always called in the derived class constructors. Whenever you create derived class object, first the base class default constructor is executed and then the derived class’s constructor finishes execution.
When would you use a protected constructor?
A protected constructor can be used to make a class effectively abstract when none of its methods are pure-virtual. It is not quite abstract in the C++ sense since friend classes can still use it without overriding, but then you would have to declare these.
Does a derived class need a constructor?
In C#, both the base class and the derived class can have their own constructor. In inheritance, the derived class inherits all the members(fields, methods) of the base class, but derived class cannot inherit the constructor of the base class because constructors are not the members of the class.
What happens if constructor is protected?
A protected constructor means that only derived members can construct instances of the class (and derived instances) using that constructor. This sounds a bit chicken-and-egg, but is sometimes useful when implementing class factories. For factory methods with side-effects.
Can we use protected for constructor?
protected: If you declare constructor as protected, any other child classes or classes within the same package can instantiate this class. First two modifiers were simple and clear to understand.
When to use the default derived class constructor?
When constructing a derived class, the derived class constructor is responsible for determining which base class constructor is called. If no base class constructor is specified, the default base class constructor will be used.
How to call protected constructor in C #?
The only way to cause a protected constructor to be called is to derive from the class and have the derived class delegate to it or to have a static method create it or some other internal method.
How to access protected method in base class from derived class?
However, if your code needs to do it the way you’re trying to and it’s not allowed, then you’ll need to either make foo () public or make Derived a friend of Base. One solution would be to declare a static protected function in Base that redirects the call to the private / protected function ( foo in the example).
What happens when the base class constructor finishes?
However, when the base class constructor finishes, the derived class constructors initialization lists are then executed. Each derived class would then have the opportunity to initialize that variable, potentially changing its value!