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While MediaInfoDLL returns metadata (Sampling Rate, Channels, Stream Size, Title...) in std::basic_string<Char> format, I need to convert to string to be able to process it later. For example mi.Get(Stream_Audio, 0, __T("Performer")) returns "Artist Name" in std::basic_string<Char> format.

Can you help me?

Thank you in advance

user3204810
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    What exactly is `Char` in your question? Is it equivalent to the builtin type `char`? If so, I have some good news... – NicholasM Jan 05 '20 at 18:52
  • Also, can you provide a link to the API documentation for the library you're using? It would help tremendously to see the exact declaration of `mi.Get`. For example, what is the type of `mi`? – NicholasM Jan 05 '20 at 18:55
  • Yes, this is builtin type char. For what I know, there's not API documentation for this library – user3204810 Jan 05 '20 at 18:56
  • What do you mean by “string”? `std::string` is a typedef name for `std::basic_string`. – Pete Becker Jan 05 '20 at 19:02
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    FYI in most builds (it is tweakable if built from source) it is mapped to wchar_t. – Jérôme Martinez Jan 05 '20 at 19:05

3 Answers3

2

Reading through the MediaInfoLib library's C++ code, it seems there are two possibilities. The library defines a type alias String, and this is the type you're seeing.

First, here is the definition of the Char and String types:

namespace MediaInfoLib {

/* ... */

//Char types
#undef  __T
#define __T(__x)     __T(__x)
#if defined(UNICODE) || defined (_UNICODE)
    typedef wchar_t Char;                    ///< Unicode/Ansi independant char
    #undef  __T
    #define __T(__x) L ## __x
#else
    typedef char Char;                       ///< Unicode/Ansi independant char
    #undef  __T
    #define __T(__x) __x
#endif

typedef std::basic_string<MediaInfoLib::Char> String;  ///< Unicode/Ansi independant string

/* ... */

}  // end namespace

If the macro UNICODE or _UNICODE was defined when the library was built, then the type is std::basic_string<wchar_t>, which is std::wstring in the standard library.

To convert this to std::string, please see this question: How to convert wstring into string?

The simplest answer there uses std::wstring_convert.

If the macro UNICODE or _UNICODE was NOT defined when the library was built, then MediaInfoLib::Char is the type char, and the MediaInfoLib::String type is std::basic_string<char> is already std::string. That is, in this case, the return type is already std::string.

NicholasM
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0

Convert std::basic_string<Char> to string ... Yes, this is builtin type char

If Char is an alias of char, then std::basic_string<Char> is already std::string. No conversion is needed, since it is the same type.

eerorika
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0

MediaInfo has ZenLib as a dependency, which in turn has its own Ztring. You can do something like this:

#include "ZenLib/Ztring.h"

MediaInfoLib::String mediainfoString = mi.Get(Stream_Audio, 0, __T("Performer"));
ZenLib::Ztring zenlibZtring(mediainfoString);
std::string stdString = zenlibZtring.To_UTF8(); // or To_Local()

You can be slightly more efficient by directly using Ztring and skipping the intermediary mediainfoString.

p.s. std::wstring_convert() was deprecated in c++17 and should probably not be used.

catalin
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