Big five
The rule of five is a C++ guideline that classes managing resources should consider defining a destructor, copy constructor, copy assignment operator, move constructor, and move assignment operator.
100 C++ Mistakes and How to Avoid Them
The rule of five is a C++ class-design pattern in which a class considers defining a destructor, copy constructor, copy assignment operator, move constructor, and move assignment operator together.
- How it is used
- Uses coordinated special members to express ownership, copying, and exclusive transfer in resource-managing classes.
- How deep it goes
- Defines all five members and demonstrates raw-pointer and smart-pointer implementations, stopping short of a complete ownership redesign.
- Examples
- Uses Page and TextSection examples showing destructive copying, deep copying, pointer moves, and unique_ptr-based defaults.
- What you can do after
- Apply the pattern to resource-owning classes and replace unsafe raw-pointer transfers with explicit move operations or smart pointers.
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Learn C++ by Example
The rule of five is a C++ design guideline that a class managing resources and declaring one relevant special member function should explicitly consider all five copy and move special member functions.
- How it is used
- Guides resource-managing classes when copy and move behavior must remain consistent.
- How deep it goes
- Explains the five operations, compiler suppression of moves, and compile-time inspection, but does not implement resource ownership.
- Examples
- Uses vector push_back and a polymorphic Blob class with static type-trait assertions.
- What you can do after
- Evaluate copy and move support with std::is_* type traits and recognize when implicit moves are unavailable.
Related concepts
- moveuses · Move semantics describe the transfer of a value or its resources to another binding or object rather than duplicating them.
- move constructorhas part · A move constructor is a C++ special member function that initializes a new object by transferring resources from another object.
- big threecontrasts with · The rule of three is a C++ resource-management guideline that a class defining a destructor, copy constructor, or copy assignment operator generally needs all three.
- special member functionconfigures · A special member function is a C++ member function with compiler-recognized semantics for object initialization, copying, moving, or destruction.
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