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IRIX 6.5 » Books » Developer »
Standard Template Library Programmer's Guide
(document number: 007-3426-004 / published: 1999-05-21) table of contents | additional info | download
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Default Constructible


Category: utilities	Component type: concept

Description

A type is DefaultConstructible if it has a default constructor, that is, if it is possible to construct an object of that type without initializing the object to any particular value.

Refinement of

Associated types

Notation

`X`	A type that is a model of DefaultConstructible
`x`	An object of type `X`

Definitions

Valid expressions

Name	Expression	Type requirements	Return type
Default constructor	`X()`		`X`
Default constructor	`X x;` [1]

Expression semantics

Name	Expression	Precondition	Semantics	Postcondition
Default constructor	`X()`
Default constructor	`X x;`

Complexity guarantees

Models

int
vector<double>

Notes

[1] The form X x = X() is not guaranteed to be a valid expression, because it uses a copy constructor. A type that is DefaultConstructible is not necessarily Assignable