Copy constructor
A copy constructor is a constructor that initializes a new object from an existing object of the same class or type.
100 C++ Mistakes and How to Avoid Them
A copy constructor is a C++ special member function that initializes an object from another object of the same class by copying its state.
- How it is used
- Explains how object initialization, resource ownership, loops, and return-by-value operations depend on copy-constructor semantics.
- How deep it goes
- Defines initialization semantics and demonstrates shallow versus deep copying, stopping short of exhaustive language rules.
- Examples
- Uses Container, Page, InputReader, range-based loops, and returning a locally constructed string to expose copying behavior.
- What you can do after
- Diagnose copying bugs, implement deep-copy behavior for resource-owning classes, and select defaulted, deleted, or move operations.
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Object-Oriented Software Design in C++
A constructor that initializes a new C++ object from an existing object of the same type.
- How it is used
- Explains hidden object copying in vector-based code and relates it to performance surprises.
- How deep it goes
- Shows a member-by-member implementation and traces repeated runtime calls, while deferring deeper copy semantics.
- Examples
- Uses an instrumented Date class, vector append and insertion, and a noncopyable ExecutivePass singleton.
- What you can do after
- Diagnose unexpected copying by instrumenting special members and evaluate when copying must be disabled.
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Related concepts
- Singleton patternused by · The Singleton pattern restricts a type or component to one shared instance within a defined scope and provides a way to access it.
- copy assignment operatorcontrasts with · A copy assignment operator is a C++ special member function that copies state from one object into an already existing object of a compatible type.
- move constructorcontrasts with · A move constructor is a C++ special member function that initializes a new object by transferring resources from another object.
- big threekind of · 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.
- initializerkind of · An initializer is a function, declaration, or language construct that establishes the initial value or state of an object, value, computation, or process.
- return value optimizationaddressed by · Return value optimization is a compiler optimization that constructs a function's returned object directly in the destination storage, eliminating unnecessary temporary objects and copy operations.
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