Re: VC++ 2005 replace _bstr_t

"Igor Tandetnik" <>
Thu, 7 Jun 2007 19:15:35 -0400
Dave King <> wrote:

 I've got a C++ app BHO i'm working on. I'm having trouble escaping
values in a _bstr_t for xml. Here's my code.

void Replace(_bstr_t& strSource, _bstr_t& strFind, _bstr_t& strRep)
   wstring tmp((wchar_t*)strSource);
   wstring::size_type begidx = tmp.find((wchar_t*)strFind);

   while(begidx != wstring::npos) {
       tmp.replace(begidx, strFind.length(), (wchar_t*)strRep);
       begidx = tmp.find_first_of((wchar_t*)strFind, begidx +
strFind.length(), begidx);

The last parameter of three-parameter overload of find_first_of is the
length of the string pointed to by the first parameter. Clearly begidx
has nothing to do with the length of strFind. Anyway, why do you use
find_first_of() and not plain old find(), as you do at the beginning?
Make it

begidx = tmp.find(strFind, begidx + strRep.length());

void escapeXML(_bstr_t& strSource)
_bstr_t strFind("<");
_bstr_t strRep("&lt;");

Replace(strSource, strFind, strRep);

_bstr_t strFind2(">");
_bstr_t strRep2("&gt;");

Replace(strSource, strFind2, strRep2);

_bstr_t strFind3("&");
_bstr_t strRep3("&amp;");

Suppose escapeXML is called with "<>". After the first Replace call it
becomes "&lt;>". After the second, "&lt;&gt;". After the third,
"&amp;lt;&amp;gt;" . Do you see a problem here?
With best wishes,
    Igor Tandetnik

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