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title _bstr_t::Assign | Microsoft Docs
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ms.date 11/04/2016
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ms.technology
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ms.topic language-reference
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_bstr_t::Assign
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C++
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Assign method
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_bstr_t::Assign

Microsoft Specific

Copies a BSTR into the BSTR wrapped by a _bstr_t.

Syntax

void Assign(  
   BSTR s  
);

Parameters

s
A BSTR to be copied into the BSTR wrapped by a _bstr_t.

Remarks

Assign does a binary copy, which means the entire length of the BSTR is copied, regardless of content.

Example

// _bstr_t_Assign.cpp  
  
#include <comdef.h>  
#include <stdio.h>  
  
int main()  
{  
    // creates a _bstr_t wrapper  
    _bstr_t bstrWrapper;   
  
    // creates BSTR and attaches to it  
    bstrWrapper = "some text";  
    wprintf_s(L"bstrWrapper = %s\n",  
              static_cast<wchar_t*>(bstrWrapper));  
  
    // bstrWrapper releases its BSTR  
    BSTR bstr = bstrWrapper.Detach();  
    wprintf_s(L"bstrWrapper = %s\n",   
              static_cast<wchar_t*>(bstrWrapper));  
    // "some text"   
    wprintf_s(L"bstr = %s\n", bstr);  
  
    bstrWrapper.Attach(SysAllocString(OLESTR("SysAllocedString")));  
    wprintf_s(L"bstrWrapper = %s\n",   
              static_cast<wchar_t*>(bstrWrapper));  
  
    // assign a BSTR to our _bstr_t  
    bstrWrapper.Assign(bstr);  
    wprintf_s(L"bstrWrapper = %s\n",   
              static_cast<wchar_t*>(bstrWrapper));  
  
    // done with BSTR, do manual cleanup  
    SysFreeString(bstr);  
  
    // resuse bstr  
    bstr= SysAllocString(OLESTR("Yet another string"));  
    // two wrappers, one BSTR   
    _bstr_t bstrWrapper2 = bstrWrapper;     
  
    *bstrWrapper.GetAddress() = bstr;  
  
    // bstrWrapper and bstrWrapper2 do still point to BSTR  
    bstr = 0;     
    wprintf_s(L"bstrWrapper = %s\n",   
              static_cast<wchar_t*>(bstrWrapper));  
    wprintf_s(L"bstrWrapper2 = %s\n",   
              static_cast<wchar_t*>(bstrWrapper2));  
  
    // new value into BSTR  
    _snwprintf_s(bstrWrapper.GetBSTR(), 100, bstrWrapper.length(),  
                 L"changing BSTR");     
    wprintf_s(L"bstrWrapper = %s\n",   
              static_cast<wchar_t*>(bstrWrapper));  
    wprintf_s(L"bstrWrapper2 = %s\n",   
              static_cast<wchar_t*>(bstrWrapper2));  
}  

bstrWrapper = some text  
bstrWrapper = (null)  
bstr = some text  
bstrWrapper = SysAllocedString  
bstrWrapper = some text  
bstrWrapper = Yet another string  
bstrWrapper2 = some text  
bstrWrapper = changing BSTR  
bstrWrapper2 = some text

END Microsoft Specific

See Also

_bstr_t Class