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C++ named requirements: CopyConstructible

Specifies that an instance of the type can be copy-constructed from an lvalue expression.

Requirements

The type T satisfies CopyConstructible if

Given

  • v, an lvalue expression of type T or const T or an rvalue expression of type const T,
  • u, an arbitrary identifier.

The following expressions must be valid and have their specified effects:

Expression Post-conditions
T u = v; The value of u is equivalent to the value of v.

The value of v is unchanged.
T(v) The value of T(v) is equivalent to the value of v.

The value of v is unchanged.

The expression v.~T() also must be valid, and, for lvalue v, the expression &v must have the type T* or const T* and must evaluate to the address of v.

 (until C++11)

Notes

Until C++11, classes that overloaded operator& were not CopyConstructible and thus were not usable in the standard library containers. This is a design decision in C++98 (instead of a defect, see LWG issue 390).

Since C++11, the standard library uses std::addressof whenever the address of an object is needed.

See also

(C++11)(C++11)(C++11)
checks if a type has a copy constructor
(class template)
(C++20)
specifies that an object of a type can be copy constructed and move constructed
(concept)

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