_bstr_t::Assign

Microsoft 特定的

將 BSTR 複製到 **_**bstr_t 所包裝的 BSTR 中。

void Assign(
   BSTR s
);

參數

• s
  要複製到 _bstr_t 所包裝之 BSTR 中的 BSTR。

備註

Assign 會執行二進位複製，這表示不論內容為何，都會複製 BSTR 的整個長度。

範例

// _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));
}

請參閱

參考

_bstr_t 類別