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Questions and Answers
In C++, can a class inherit from multiple classes? If so, provide an example using the classes Transmitter and Receiver.
In C++, can a class inherit from multiple classes? If so, provide an example using the classes Transmitter and Receiver.
Yes, a class can inherit from multiple classes. For example: class Phone: public Transmitter, public Receiver { ... };.
If a class Mermaid inherits privately from Woman and Fish, will a class derived from Mermaid have access to public members of Woman and Fish?
If a class Mermaid inherits privately from Woman and Fish, will a class derived from Mermaid have access to public members of Woman and Fish?
No, a class derived from Mermaid will not have access to the public or protected members of Woman and Fish due to the private inheritance.
A Phone class inherits from Transmitter and Receiver. If a Phone object obj is created, can obj.Transmit() and obj.Receive() be called? Assume the methods are defined in their respective classes.
A Phone class inherits from Transmitter and Receiver. If a Phone object obj is created, can obj.Transmit() and obj.Receive() be called? Assume the methods are defined in their respective classes.
Yes, obj.Transmit() and obj.Receive() can be called as the derived class inherits the functionality of both base classes.
Given a Phone object obj and a Transmitter pointer tPtr = &obj;, can tPtr->Receive() be called?
Given a Phone object obj and a Transmitter pointer tPtr = &obj;, can tPtr->Receive() be called?
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If a Phone object obj is assigned to both a Transmitter pointer tPtr and a Receiver pointer rPtr, can tPtr be used to call methods of Receiver and rPtr be used to call methods of Transmitter?
If a Phone object obj is assigned to both a Transmitter pointer tPtr and a Receiver pointer rPtr, can tPtr be used to call methods of Receiver and rPtr be used to call methods of Transmitter?
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What happens when multiple base classes have a function with the same signature, and a derived class inherits from them?
What happens when multiple base classes have a function with the same signature, and a derived class inherits from them?
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A class Child inherits both ParentA and ParentB. Both base classes have a void display() method. How can the Child class method of display be called without ambiguity?
A class Child inherits both ParentA and ParentB. Both base classes have a void display() method. How can the Child class method of display be called without ambiguity?
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A Phone class inherits publicly from Transmitter and Receiver. Can a Phone object replace an object of Transmitter or Receiver?
A Phone class inherits publicly from Transmitter and Receiver. Can a Phone object replace an object of Transmitter or Receiver?
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In multiple inheritance, what causes the 'ambiguous call' problem when a derived class inherits methods with the same name from multiple base classes?
In multiple inheritance, what causes the 'ambiguous call' problem when a derived class inherits methods with the same name from multiple base classes?
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How can a programmer explicitly specify which base class's method to call when dealing with an ambiguous inheritance situation?
How can a programmer explicitly specify which base class's method to call when dealing with an ambiguous inheritance situation?
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In a multiple inheritance scenario, if a class inherits from two classes that both inherit from a common base class, how many copies of the base class object does the derived class initially have?
In a multiple inheritance scenario, if a class inherits from two classes that both inherit from a common base class, how many copies of the base class object does the derived class initially have?
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Why does attempting to resolve the ambiguous method call by directly calling the base method (e.g., obj.Vehicle::GetMaxLoad()) not work in multiple inheritance?
Why does attempting to resolve the ambiguous method call by directly calling the base method (e.g., obj.Vehicle::GetMaxLoad()) not work in multiple inheritance?
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How can a programmer resolve the ambiguity of data members inherited from multiple paths in a multiple inheritance hierarchy?
How can a programmer resolve the ambiguity of data members inherited from multiple paths in a multiple inheritance hierarchy?
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What problem does virtual inheritance aim to solve in multiple inheritance?
What problem does virtual inheritance aim to solve in multiple inheritance?
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In virtual inheritance, how many copies of an anonymously inherited base class object exist in the most derived class?
In virtual inheritance, how many copies of an anonymously inherited base class object exist in the most derived class?
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When is the usage of virtual inheritance necessary, and what is the alternative if virtual inheritance is not used in multiple inheritance?
When is the usage of virtual inheritance necessary, and what is the alternative if virtual inheritance is not used in multiple inheritance?
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In the given example, what would happen if the AmphibiousVehicle class tried to directly assign a value to weight without specifying whether it belongs to LandVehicle or WaterVehicle before virtual inheritance is used?
In the given example, what would happen if the AmphibiousVehicle class tried to directly assign a value to weight without specifying whether it belongs to LandVehicle or WaterVehicle before virtual inheritance is used?
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In the context of the 'BS Student', 'MS Student', and 'PhD Student' example, why might a programmer choose to use virtual inheritance for the 'Student' base class in the case of an 'MS/PhD Student'?
In the context of the 'BS Student', 'MS Student', and 'PhD Student' example, why might a programmer choose to use virtual inheritance for the 'Student' base class in the case of an 'MS/PhD Student'?
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Study Notes
Multiple Inheritance in C++
- C++ allows a class to inherit from multiple classes.
- Example:
class Phone : public Transmitter, public Receiver - Public inheritance: Derived classes access public/protected members of base classes.
- Private inheritance: Derived classes don't access public/protected members of base classes.
- The derived class inherits data members and functions from all base classes.
- An object of a derived class can perform all tasks of the base classes.
- Example:
Phoneobject canTransmit()andReceive().
Calling Base Class Functions
- In public multiple inheritance, a derived class object can be treated as an object of any of its base classes.
-
Transmitter * tPtr = &obj;andtPtr->Transmit()is valid. - Calling functions from different base classes through a pointer to a derived class is not possible directly.
- Example:
tPtr->Receive();(error)
Problems with Multiple Inheritance
- Ambiguity arises when multiple base classes have functions with the same signature.
- Example:
LandVehicleandWaterVehicleclasses each haveGetMaxLoad(). - The compiler doesn't know which
GetMaxLoad()to call. - Solution: Explicitly specify the base class when calling the function.
Example
-
obj.LandVehicle::GetMaxLoad(); - This issue can also occur in multiple levels of inheritance.
- If an intermediate base class has a function with the same signature as a function in one of the multiple direct base classes, then there can be issues too.
Virtual Inheritance
- Virtual inheritance addresses issues of multiple copies within inheritance hierarchy.
- A single copy of the base class is created in derived classes.
- Example:
-
class Vehicle{ protected: int weight; }; -
class LandVehicle : public virtual Vehicle {}; -
class WaterVehicle : public virtual Vehicle {};
-
- A reduced number of copies of data members and methods from base classes is the benefit.
Virtual Inheritance Example (in Code)
-
class AmphibiousVehicle : public LandVehicle, public WaterVehicle { public: AmphibiousVehicle(){ weight = 10; } }; - This example demonstrates a
Vehicleclass inherited virtually byLandVehicleandWaterVehicle, then inherited further byAmphibiousVehicle, eliminating redundant copies.
When to use Virtual Inheritance
- Use when needing only one copy of a base class in the inheritance hierarchy to reduce redundancy.
- Avoids issues with ambiguous function calls or data member copies across inheritance chains.
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Description
This quiz covers the concept of multiple inheritance in C++, where a class can inherit from multiple base classes. It explores public and private inheritance, calling base class functions, and the potential problems that may arise, such as ambiguity. Test your understanding of these key concepts in C++ programming.
