C++ object copying: which special member is used to make a copy of one object from another object of the same class type?

Introduction / Context:
C++ defines special member functions to control copying, moving, construction, and destruction. When a new object must be initialized as a copy of an existing object, a particular special member is selected by the compiler. This question asks you to name that member precisely.

Given Data / Assumptions:

• Two objects of the same class type are involved: a source and a destination.
• Initialization syntax such as T b = a; or T b(a); is used.
• No exotic conversion or template trickery; standard behavior is assumed.

Concept / Approach:

The copy constructor initializes a new object from an existing object. Its canonical signature is T(const T&). The ordinary constructor builds objects from scratch (possibly with parameters). The destructor tears objects down at end of lifetime. The “default constructor” is the zero-argument constructor and is unrelated to copying. Recognizing which special member applies to each situation is core C++ knowledge for managing resource ownership and value semantics correctly.

Step-by-Step Solution:

Verification / Alternative check:

Observe behavior when the copy constructor is deleted or private: the above forms of initialization become ill-formed, demonstrating the copy constructor’s role. Tools like compiler diagnostics explicitly mention “copy constructor is deleted.”

Why Other Options Are Wrong:

constructor: too general; does not specifically denote copying.

destructor: runs at end-of-life, not at initialization.

default constructor: creates objects without arguments, not from another object.

Common Pitfalls:

• Confusing copy construction with copy assignment (operator=), which replaces the state of an already-initialized object.
• Neglecting to implement the rule of three/five/zero for resource-owning types.

Final Answer:

copy constructor