C++ Topics and Explanations
Re: Converting BSTR to CString
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Posted by William Baldwin on November 10, 203 at 08:17:05:

In Reply to: Converting BSTR to CString posted by SRA on July 10, 203 at 01:12:30:

: I want to know the easy method to convert BSTR to CString

: -sr

BSTR GetBSTR()
{
_bstr_t bstr1(_T("This is the test string."));

BSTR bstr;

bstr = bstr1.copy();

return bstr;
}


CComBSTR GetComBSTR()
{
CComBSTR bstr("This is the test string.");

return bstr;
}


void CVbsDlg::ShowBSTR(BSTR bstr)
{
_bstr_t bstrStart(bstr);

CString s;

s.Format(_T("%s"), (LPCTSTR)bstrStart);

AfxMessageBox(s);

}

Conversions
So, let's get to it. Here are the conversion techniques:

Converting BSTR to _bstr_t
// BSTR to _bst_t

BSTR bstrStart = GetBSTR();

// use the constructor
_bstr_t bstrFinal(bstrStart);

ShowBSTR(bstrFinal);

// Use the = operator
bstrFinal = bstrStart;

ShowBSTR(bstrFinal);

Converting a _bstr_t to BSTR

You may want to get a BSTR from a _bstr_t class.

// _bstr_t to BSTR

_bstr_t bstrStart(_T("This is the test string."));

BSTR bstrFinish;

// use _bstr_t::copy member function
bstrFinish = bstrStart.copy();

ShowBSTR(bstrFinish);

// use = operator
bstrFinish = bstrStart;

ShowBSTR(bstrFinish);

Converting a CComBSTR to BSTR

You may want to get a BSTR from a CComBSTR class.

// CComBSTR to BSTR
CComBSTR bstrStart(_T("This is the test string."));

BSTR bstrFinish;

// use the = operator
bstrFinish = bstrStart;

ShowBSTR(bstrFinish);

// use the Copy member function
bstrFinish = bstrStart.Copy();

ShowBSTR(bstrFinish);

Converting _bstr_t to CComBSTR

// _bstr_t to CComBSTR
_bstr_t bstrStart(_T("This is the test string."));

CComBSTR bstrFinish;

bstrFinish.AppendBSTR(bstrStart);

ShowBSTR(bstrFinish);

Converting BSTR to C String

(Note: conversion that only works in Unicode)

// BSTR to C String

BSTR bstrStart;

bstrStart = GetBSTR();

TCHAR szFinal[255];

// direct conversion from BSTR to LPCTSTR only works
// in Unicode
_stprintf(szFinal, _T("%s"), (LPCTSTR)bstrStart);
AfxMessageBox(szFinal);

_bstr_t bstrIntermediate(bstrStart); // convert to
// _bstr_t
CString strFinal;

// you have to go through _bstr_t to have it work in ANSI
// and Unicode
_stprintf(szFinal, _T("%s"), (LPCTSTR)bstrIntermediate);

// Or, using MFC

strFinal.Format(_T("%s"), (LPCTSTR)bstrIntermediate);

AfxMessageBox(strFinal);

Converting _bstr_t to C String

(this works in both ANSI and Unicode)

_bstr_t bstrStart(_T("This is the test string."));
TCHAR szFinal[255];

_stprintf(szFinal, _T("%s"), (LPCTSTR)bstrStart);

AfxMessageBox(szFinal);

Converting CComBSTR to LPCTSTR

(not possible; must go through _bstr_t)

// CComBSTR to C String
CComBSTR bstrStart("This is the test string.");

_bstr_t bstrIntermediate(bstrStart);

TCHAR szFinal[255];

_stprintf(szFinal, _T("%s"),
(LPCTSTR)bstrIntermediate);

AfxMessageBox(szFinal);

Converting LPCTSTR to _bstr_t

Use a constructor or = operator

// LPCTSTR to _bstr_t

LPCTSTR szStart = _T("This is the text string");

// Use the constructor
_bstr_t bstrFinal(szStart);

ShowBSTR(bstrFinal);

// or use = operator
bstrFinal = szStart;

ShowBSTR(bstrFinal);

Converting LPCTSTR to CComBSTR

Use a constructor or CComBSTR::Append function

// LPCTSTR to CComBSTR

// Use a constructor

LPCTSTR szStart = _T("This is the text string");

// Use the constructor
CComBSTR bstrFinal(szStart);

ShowBSTR(bstrFinal);

// Or use the Append function
bstrFinal.Empty();
bstrFinal.Append(szStart);

ShowBSTR(bstrFinal);



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