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What is the valid class declaration header for the derived class d with base classes b1 and b2 A class d public b1 public b2 B class d class b1 class b2 C class d public b1 b2 D class d b1 b2?
Wiki User
∙ 7y ago
What is the valid class declaration header for the derived class d with base classes b1 and b2?
A. class d : public b1, public b2 {/*...*/};
B. class d : class b1, class b2 {/*...*/};
C. class d : public b1, b2 {/*...*/};
D. class d : b1, b2 {/*...*/};
The answer is A, C and D.
B is not valid because "class" is not a valid access specifier.
All the others are valid because private access is the default when the access specifier is omitted. Note that if class D were declared using the struct prefix, inheritance would default to public access rather than private.
Wiki User
∙ 7y ago
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What is derived class in brief?
A derived class is any class that inherits from one or more other classes, known as base classes. The derived class inherits the sum total of all public and protected members of all its base classes, including their base classes. The derived class is a more specialised form of its base classes. Any members of the base classes that are declared virtual can be overridden, such that calling the base class method directly actually invokes the derived class method, thus enabling polymorphic behaviour.
Which base class member functions are not inherited by a derived class?
Derived classes only inherit the protected and public members of their base classes. Private member functions cannot be inherited by a derived class.
What is the difference between the direct and indirect base class?
Direct base classes are those that are specified in a derived class' inheritance declaration. Indirect base classes are those that are inherited via the direct base classes. class A{}; class B : public A{}; class C : public B{}; With respect to C, B is direct while A is indirect. With respect to B, A is direct.
A pure virtual function is a virtual function that has?
A pure-virtual function is a function that must be overridden in derived classes. You simply add "=0" to the end of the function declaration. class AbstractClass { public: virtual void DoSomething()=0; // Pure-virtual. };
How can you protect derived classes from breaking when you change the internal parts of the base class?
You protect derived classes from breaking when you change the internal parts of the base class by making sure that the public (or protected) parts of the base class do not change. Only the private parts may change. If the public interface changes, then the derived class must often change.
What is derived class in brief?
A derived class is any class that inherits from one or more other classes, known as base classes. The derived class inherits the sum total of all public and protected members of all its base classes, including their base classes. The derived class is a more specialised form of its base classes. Any members of the base classes that are declared virtual can be overridden, such that calling the base class method directly actually invokes the derived class method, thus enabling polymorphic behaviour.
Which base class member functions are not inherited by a derived class?
Derived classes only inherit the protected and public members of their base classes. Private member functions cannot be inherited by a derived class.
What is the difference between the direct and indirect base class?
Direct base classes are those that are specified in a derived class' inheritance declaration. Indirect base classes are those that are inherited via the direct base classes. class A{}; class B : public A{}; class C : public B{}; With respect to C, B is direct while A is indirect. With respect to B, A is direct.
Why is an array called a derived data type?
An array is not a derived data type at all. In order to be derived there has to be a base class and an array has no base class. Here is the basic declaration of the std::array template class from the <array> header file: template<class _Ty, size_t _Size> class array { // fixed size array of values // ... }; A vector, on the other hand, is derived (from the <vector> header file): template<class _Ty, class _Alloc = allocator<_Ty>> class vector : public _Vector_alloc<!is_empty<_Alloc>::value, _Vec_base_types<_Ty, _Alloc>> { // varying size array of values // ... };
A pure virtual function is a virtual function that has?
A pure-virtual function is a function that must be overridden in derived classes. You simply add "=0" to the end of the function declaration. class AbstractClass { public: virtual void DoSomething()=0; // Pure-virtual. };
How can you protect derived classes from breaking when you change the internal parts of the base class?
You protect derived classes from breaking when you change the internal parts of the base class by making sure that the public (or protected) parts of the base class do not change. Only the private parts may change. If the public interface changes, then the derived class must often change.
What is sub classing in c plus plus?
Class in C++ is just the same meaning as in any other OO(object-oriented) languages. In the world of OO, anything are classes, which have properties, function to work. In other words, class is a method to organize things to work together.
When should a member of a class be declared public?
When the member needs to be accessible from outside of the class. Private members are only accessible from within the class itself, including friends of the class. Protected members are the same as private members but are also accessible to derived classes. Derived classes therefore inherit both the protected and public members of its base classes.
Give an example of constructor and destructor in derived class?
class superclass { public: superclass() {... } // c'tor public: virtual ~superclass() {... } // d'tor }; // superclass class derived: public superclass { public: derived() : superclass() { ... } // derived c'tor public: virtual ~derived() {... } // derived d'tor }; // derived class
How can a base class protect derived classes so that changes to the base class will not affect them explain with example?
In order for a base class to protect derived classes, so that changes to the base class do not affect the derived classes, you must make sure that the public interface exposed by the base class does not change when the implementation of those public methods do change. You can also prevent inadvertant access to the base class attributes from the derived class, by making them private. class base { public: base(...) {...}; /* constructor */ base~(...) {...}; /* destructor */ method(...) {...}; /* other public methods */ private: ... etc. } class child : base { public: ... private: ... } So long as the calling sequence and functionality (interface) of the base class public methods do not change, the implementation of those public methods can change, and the private methods and attributes can change, without impacting any child class.
What is multilevel inheritance in C plus plus?
Multi-level inheritance involves at least 3 classes, a, b and c, such that a is derived from b, and b is derived from c. c is therefore the least-derived base class, b is an intermediate base class and a is the most-derived class.
Can a derived class make a public base function private true or false?
True. A derived class can make a public base function private. The derived function is private, within the derived class, but public in other contexts.
