Re: stl string find issue

"PaulH" <>
30 Jun 2006 06:13:02 -0700
*dusts off Effective C++*
Yup, you're right.
Thanks for the tip.


Thomas Tutone wrote:

PaulH wrote:

I have a function that is stripping off some XML from a configuration
file. But, when I do a search for the pieces I want to strip, the
std::string::find() function always returns std::string::npos (-1).

I can print out the config string at the beginning of CleanCfgFile(),
and the strings are there exactly the way I'm looking for them. So, the
question is, what am I doing wrong?

    std::vector<TCHAR> configString(bufLen);
    //populate configString....

bool CleanCfgFile(std::string *cfgFile)
    TCHAR XMLHeader[] = _T("<?xml");
    std::string::size_type start = cfgFile->find(XMLHeader);
    //start == std::string::npos!

Why am I using a vector and not a string in Function(), you ask? It's
just easier for the rest of the program. I could probably change it if
that's the problem... I just thought you could cast between the two and
be fine.

You've answered your own question. Assuming for the moment that a
"TCHAR" is just a typedef for a char, using reinterpret_cast<> to cast
between a std::string* and a std::vector<char> has behavior so
undefined, it's hard to know where to begin. But here's a hint - how
std::string is implemented is implementation defined. If you have a
copy of Scott Meyers' Effective STL, take a look at Item 15, where he
discusses several different common implementations of std::string.
There is certainly no guarantee - it's not even particularly likely -
that std::string shares a common internal layout and implementation
with std::vector<char>.

Best regards,


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