C++ concepts: DefaultConstructible
Specifies that an instance of the type can be default constructed.
Requirements
The type T satisfies DefaultConstructible if
Given
-
u, an arbitrary identifier
The following expressions must be valid and have their specified effects
| Expression | Post-conditions |
|---|---|
| T u | The object u is default-initialized
|
| T u{} | The object u is value-initialized or aggregate-initialized.
|
| T()
T{} |
A temporary object of type T is value-initialized or aggregate-initialized.
|
Notes
For objects of non-aggregate class type, a public default constructor must be defined (either user-defined or implicitly defined) to satisfy DefaultConstructible.
Non-const objects of non-class object type are always DefaultConstructible.
Const non-class types are not DefaultConstructible.
Const aggregate types are not DefaultConstructible if any of their members is an object of non-class type.
Non-object types (function types, reference types, and the (possibly cv-qualified) type void) as well as the const non-object types are never DefaultConstructible
See also
| checks if a type has a default constructor (class template) |