Error in converting BSTR to CString

Question

I using Visual C++ 2008 and ADO to access a database and obtain a field value like this:

_variant_t vtValue;

AfxVariantInit(&vtValue);

vtValue = m_pRecordset->Fields->GetItem(_variant_t(strFieldName))->GetValue();

If (vtValue.vt == VT_BSTR)
{
  strValue = vtValue.bstrVal;
  TRACE(_T(“Field value is %s.\r\n”), strValue);    // Cause CrtDbgReport: String too long or IO Error
}
else
{
   .. other codes…
}

The TRACE statement for strValue will cause the following error:

“CrtDbgReport: String too long or IO Error”

I just check strValue and found it is a Chinese string with only 6 characters, nothing special. Why it will cause the error?

Thanks

[This Answer](http://stackoverflow.com/a/1685831/332733) may be useful — Mgetz, Mar 03 '14 at 16:57

score 1 · Answer 1 · answered Mar 03 '14 at 17:37

A BSTR is a composite data type that consists of a length prefix, a data string, and a terminator, you can not assign it to CString directly as CString doesn't have the length prefix.

You can use the smart point class _bstr_t to do the conversion.

strValue = (TCHAR*)(_bstr_t)vtValue;

Error in converting BSTR to CString

1 Answers1