c_str() VS wx_str() for wxString Format output

[ollydbg]

I see many code in our code base

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Function("xxxx %s", songwxString.wx_str());


Also, some use c_str().

What is the preferred way.

I look at the document, in wx2.8.12

wxString::c_str
const wxChar * c_str() const

Returns a pointer to the string data (const char* in ANSI build, const wchar_t* in Unicode build).

Note that the returned value will not be convertible to char* or wchar_t* in wxWidgets 3, consider using char_str or wchar_string if you need to pass string value to a function expecting non-const pointer.

No official document in 2.8.12, but I see such code in the header file

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   // identical to c_str(), for wxWin 1.6x compatibility
   const wxChar* wx_str()  const { return c_str(); }


Note, c_str just return a pointer point to the internal buffer.

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 const wxChar* c_str() const { return m_pchData; }
 const wxChar* data() const { return m_pchData; }
So, they are the same.


Now, in wx 3.0 (trunk), I see: wx_str

const wxStringCharType* wxString::wx_str    (       )    const

Explicit conversion to C string in the internal representation (either wchar_t* or UTF-8-encoded char*, depending on the build).

But c_str are some different

wxCStrData wxString::c_str    (       )    const

Returns a lightweight intermediate class which is in turn implicitly convertible to both const char* and to const wchar_t*.

Given this ambiguity it is mostly better to use wc_str(), mb_str() or utf8_str() instead.

Please see the Unicode Support in wxWidgets for more information about it.

Note that the returned value is not convertible to char* or wchar_t*, use char_str() or wchar_str() if you need to pass string value to a function expecting non-const pointer.

See Also
   wc_str(), utf8_str(), c_str(), mb_str(), fn_str()

Not quite understand the document.

Any suggestions?


EDIT
A former discussion about Question about wx_str() and c_str(), we later remove the #if wxCHECK_VERSION(2, 9, 0) clause, and all is wx_str() now.