String types in C++: how to convert from LPWSTR to LPSTR?

Question

I am calling a C++ method which returns LPWSTR (the string contains a filepath), but I need to convert this to a LPSTR to continue.

I never used C++ before and even though the different string types are explained in detail here: http://www.codeproject.com/Articles/76252/What-are-TCHAR-WCHAR-LPSTR-LPWSTR-LPCTSTR-etc , I got confused.

When I cast LPWSTR to LPTSTR (which should equal LPSTR in my app), I get exactly one Unicode Symbol. While I guess that casting isn't appropriate in this case, I don't understand why it returns only one character instead of interpreting all the 2-byte-characters of the LPWSTR somehow as 1-byte-characters. I found references to the WideCharToMultiByte function, which apparently can convert LPWSTR to std::string , which I in turn can not cast to LPSTR either.

So is there an somewhat easy way to obtain an LPSTR from the LPWSTR ?

Answer 1

Casting a pointer to another type of pointer will not alter or convert what the original pointer points at.

You should be able to call c_str() on a std::string , and cast that to LPSTR , I think. So, use WideCharToMultiByte (if it does indeed, as you say, convert to a std::string ) and call c_str on the result. This will give you a constant string pointer ( LPCSTR ). You can copy it (eg via strdup ) and cast the result to LPSTR .

The returned pointer will then refer to a character string allocated using strdup , so should be passed to free at some point when the string is no longer needed.

The WideCharToMultiByte function that I am familiar with from the Windows API (see documentation ) converts directly from a wide-character string to a multi-byte encoded string without going via std::string , although it still requires allocation of a buffer to hold the output string. You may be able to use it instead.