How do I get wcsftime to work in Visual Studio CRT?

Question

The implementation of wcsftime that ships with the Visual Studio CRT seems to have a completely unbelievable bug! It just doesn't support unicode, as far as I can tell.

Internally, it translates to single-byte (using the current single-byte codepage), then calls strftime, then goes back to multibyte. What a joke! Why do they ship a wide version if it's no better than the narrow one?

If I call wcsftime(L"ümlaut ş"), the umlaut works (because it's contained in Latin-1) but the s-cedilla won't (it comes out as L"ümlaut ?").

All I want is to write a wrapper around wcsftime that returns UTF-8 data, but I can't seem to get the full range of Unicode out of wcsftime (let alone strftime), no matter what I do.

Are these functions just fundamentally broken in the CRT? Do I have to ship my own implementation just to get strftime format strings working in my cross-platform application?

Answer 1

It is a known problem with wcsftime, you simply should not format date and time with characters in format that are not from selected locale. You can also try using GetDateFormat / GetTimeFormat functions, but I am not sure if they will work as you want. Other solution is to encode all characters to hex (for example "ş" <-> "@015E") before calling wcsftime and decode after calling it.

Answer 2

For the record, my solution was to implement my own strftime (adding it to the list of fourteen groups of ISO C functions I already have to re-implement on Windows). My strftime uses locale correctly, takes a UTF-8 format string, and replaces the tokens appropriately with data obtained directly from GetLocaleInfoEx and GetDateFormatW, unlike the broken CRT version. Sigh.