Converting between UTF-8 strings and UTF-16 strings in C++/WinRT

Raymond Chen

C++/WinRT provides a pair of functions for converting between UTF-8 strings (with code units represented as char) and UTF-16 strings (code units of wchar_t).

The to_string function takes a std::wstring_view of UTF-16 code units and converts them to a UTF-8 string, represented as a std::string.

Conversely, the to_hstring function takes a std::string_view of UTF-8 code units and converts them to a UTF-16 string, represented as a winrt::hstring.

The argument to to_string and to_hstring can be anything convertible to the corresponding string view type. Types that fall into this category include

Type Converts to
std::string std::string_view
std::wstring std::wstring_view
winrt::hstring std::wstring_view

We’ll put these conversions to good use next time.

4 comments

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  • Luan Vitor Simião Oliveira 0

    should there also be a to_u16string? and versions that take a u8string_view?

  • Erik Weitenberg · Edited 0

    I suppose I get why the wstrings are named like that (string for wide characters) but I’m not sure what to think of hstring (high characters??). You explained a while ago that the H in HRESULT likely means ‘handle’, but I’m not sure that makes sense here.. Any clues? 🙂

    • Harry Johnston 0

      The documentation says that winrt::hstring encapsulates HSTRING, and that HSTRING is a handle to a Windows Runtime string, so I think your guess is correct. The documentation for HSTRING adds “use HSTRING to represent immutable strings in the Windows Runtime” and there are various associate API functions, e.g., WindowsCreateString and WindowsDeleteString.

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