C++ concepts: DefaultConstructible

 

C++

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C++ concepts

Basic
DefaultConstructible CopyAssignable CopyConstructible	MoveAssignable (C++11) MoveConstructible (C++11) Destructible
Library-Wide
EqualityComparable LessThanComparable Swappable (C++11) ValueSwappable (C++11)	NullablePointer (C++11) Hash (C++11) Allocator
Container
Container SequenceContainer ReversibleContainer	AssociativeContainer AllocatorAwareContainer UnorderedAssociativeContainer (C++11)
Container Elements
CopyInsertable (C++11) MoveInsertable (C++11)	EmplaceConstructible (C++11)
Iterator
Iterator OutputIterator InputIterator	ForwardIterator BidirectionalIterator RandomAccessIterator
Stream I/O
FormattedInputFunction UnformattedInputFunction	FormattedOutputFunction UnformattedOutputFunction
Random Numbers
SeedSequence (C++11) RandomNumberEngine (C++11)	RandomNumberDistribution (C++11) UniformRandomNumberGenerator (C++11) RandomNumberEngineAdaptor (C++11)
Concurrency
BasicLockable (C++11) Lockable (C++11) TimedLockable (C++11)	Mutex (C++11) TimedMutex (C++11) SharedMutex (C++14)
Other
CharTraits pos_type off_type Clock (C++11) BitmaskType	UnaryTypeTrait (C++11) BinaryTypeTrait (C++11) TransformationTrait (C++11) TrivialClock (C++11) LiteralType (C++11)

 

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.
T() T{}	A temporary object of type T is value-initialized.

See also

is_default_constructibleis_trivially_default_constructibleis_nothrow_default_constructible (C++11)(C++11)(C++11)	checks if a type has a default constructor (class template)