title	_bstr_t class
description	Learn more about: _bstr_t class
ms.date	02/02/2021
f1_keywords	_bstr_t
helpviewer_keywords	BSTR object _bstr_t class BSTR object [C++], COM encapsulation

_bstr_t class

Microsoft Specific

A _bstr_t object encapsulates the BSTR data type. The class manages resource allocation and deallocation through function calls to SysAllocString and SysFreeString and other BSTR APIs when appropriate. The _bstr_t class uses reference counting to avoid excessive overhead.

Members

Construction

Constructor	Description
_bstr_t	Constructs a _bstr_t object.

Operations

Function	Description
Assign	Copies a BSTR into the BSTR wrapped by a _bstr_t.
Attach	Links a _bstr_t wrapper to a BSTR.
copy	Constructs a copy of the encapsulated BSTR.
Detach	Returns the BSTR wrapped by a _bstr_t and detaches the BSTR from the _bstr_t.
GetAddress	Points to the BSTR wrapped by a _bstr_t.
GetBSTR	Points to the beginning of the BSTR wrapped by the _bstr_t.
length	Returns the number of characters in the _bstr_t.

Operators

Operator	Description
operator =	Assigns a new value to an existing _bstr_t object.
operator +=	Appends characters to the end of the _bstr_t object.
operator +	Concatenates two strings.
operator !	Checks if the encapsulated BSTR is a NULL string.
operator == operator != operator < operator > operator <= operator >=	Compares two _bstr_t objects.
operator wchar_t* operator char*	Extract the pointers to the encapsulated Unicode or multibyte BSTR object.

END Microsoft Specific

Requirements

Header: <comutil.h>

Lib: comsuppw.lib or comsuppwd.lib (For more information, see /Zc:wchar_t (wchar_t is native type))

See also

Compiler COM support classes