Virtual destructor
A virtual destructor is a destructor whose dynamic dispatch ensures that destroying an object through a base-class interface invokes the derived-class destructor.
100 C++ Mistakes and How to Avoid Them
A virtual destructor is a destructor declared virtual so destruction through a base-class interface dispatches to the derived object's destructor.
- How it is used
- Protects cleanup when polymorphic objects are deleted through base-class pointers or stored in containers.
- How deep it goes
- Explains the rule, demonstrates undefined behavior and leakage, and contrasts failing and corrected destruction output.
- Examples
- Uses Shape and Square resource cleanup plus Person and Employee objects in polymorphic containers.
- What you can do after
- Diagnose/debug leaks from base-pointer deletion and correct polymorphic base classes with virtual destructors.
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Learn C++ by Example
A virtual destructor is a destructor declared virtual so that deleting an object through a base-class pointer invokes the appropriate derived-class destructor.
- How it is used
- Enables safe cleanup when polymorphic objects are accessed and deleted through base-class pointers.
- How deep it goes
- Explains destructor dispatch, undefined behavior, and v-table placement, then stops short of detailed implementation mechanics.
- Examples
- Uses a Blob and DerivedBlob race hierarchy to contrast base-pointer deletion with derived-pointer deletion.
- What you can do after
- Apply it by declaring a defaulted virtual destructor in a polymorphic base class before deleting derived objects through base pointers.
Related concepts
- undefined behavioraddresses · Undefined behavior is program execution for which the applicable language or system specification imposes no requirements on the resulting behavior or effects.
- memory leakaddresses · A memory leak is the unintended retention of allocated memory that a program no longer needs, preventing that memory from being reclaimed for reuse.
- superclassused by · A superclass is a class from which another class inherits members, structure, state, or behavior.
- destructorkind of · A destructor is an operation associated with an object or value that performs cleanup when its lifetime ends.
- polymorphic array elementcontrasts with · A polymorphic array element is an array element accessed through a base-class array interface even though the stored elements have a derived class type.
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