Big three
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.
Object-Oriented Software Design in C++
A C++ class-design rule grouping the destructor, copy constructor, and copy assignment operator as special members that may need coordinated implementation.
- How it is used
- Uses coordinated special-member implementation to control copying and destruction while diagnosing hidden vector operations.
- How deep it goes
- Defines the rule and demonstrates member-wise copying, assignment, self-assignment protection, and logged runtime calls.
- Examples
- Uses an instrumented Date class, an Appointments vector, append and insertion operations, and constructor or destructor logs.
- What you can do after
- Diagnose/debug with instrumentation by identifying implicit copies, assignments, destructions, allocations, and deallocations.
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100 C++ Mistakes and How to Avoid Them
The big 3 is the C++ special-member-function set consisting of a copy constructor, copy assignment operator, and destructor.
- How it is used
- Uses the big three to preserve correctness when classes manage dynamic or limited resources.
- How deep it goes
- Explains copying and destruction through shared-resource failure, deep copying, assignment, and move-enabled modernization.
- Examples
- Uses Page and TextSection listings to contrast shared pointers, uniqueness-preserving copies, and defaulted move operations.
- What you can do after
- Apply it by implementing deep-copy construction, copy assignment, and destruction, then modernize ownership with unique_ptr and move operations.
Read how 100 C++ Mistakes and How to Avoid Them explains big three →
Learn C++ by Example
The rule of three is a C++ resource-management guideline stating that a class defining a destructor, copy constructor, or copy assignment operator will generally need to define all three.
- How it is used
- Guides resource-owning class design and prompts checks of generated special member functions.
- How deep it goes
- Defines the guideline and links it to move operations, but stops short of implementing ownership or copy behavior.
- Examples
- Uses an abstract Blob type, static type-trait assertions, and vector push_back overloads to expose copying and moving behavior.
- What you can do after
- Evaluate whether a class supports destruction, copying, moving, and construction through C++ type traits.
Related concepts
- big fivecontrasts with · 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.
- destructorincludes · A destructor is an operation associated with an object or value that performs cleanup when its lifetime ends.
- copy constructorincludes · A copy constructor is a constructor that initializes a new object from an existing object of the same class or type.
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