Why Are Pointers/References Necessary for Polymorphism in C ?

Polymorphism Without Pointers/References: Unraveling the Enigma

The concept of polymorphism relies heavily on the usage of pointers or references. While pointers may seem intuitively helpful, the role of references in this context often raises questions. This article aims to shed light on the fundamental reasons behind the necessity of pointers/references for polymorphism implementation.

Understanding Pointers and References

Pointers and references are powerful tools in C that provide indirect access to objects. Pointers store the memory address of an object, while references provide an alias to an existing object, effectively allowing access to the original object without creating a copy.

Polymorphism and Dynamic Binding

Polymorphism enables objects of different derived classes to respond to the same method call based on their actual type at runtime. This dynamic binding behavior is achieved through virtual function tables. These tables contain pointers to the implementations of virtual methods for each derived class.

Role of Pointers/References

When passing a derived class object to a base class function via a pointer or reference, the actual object's type can be determined at runtime. This is because the pointer or reference holds the memory address or alias of the object, which allows the compiler to access the virtual function table and resolve the method call accordingly.

Consequences of Using Value Types

If a base class object holds a copy of a derived class object passed by value (without a pointer or reference), the compiler cannot determine the actual type of the object at runtime. This is because the copy of the object has no connection to the virtual function table of the derived class. Consequently, polymorphism fails, leading to calls to the base class method instead of the derived class method.

Conclusion

Polymorphism in C requires pointers or references to enable dynamic binding and determine the actual type of derived class objects at runtime. Without pointers or references, the compiler cannot determine the virtual function table to use, resulting in the failure of polymorphism and the loss of the ability to handle objects based on their actual type.

The above is the detailed content of Why Are Pointers/References Necessary for Polymorphism in C ?. For more information, please follow other related articles on the PHP Chinese website!