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()
| 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) |
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