These functions do not work as specified by the C or C++ standards:

• fopen_s and freopen

  These C functions will not propagate the u exclusivity attribute to the low-level interface.

• towupper and towlower

  These C functions will only handle A, ..., Z and a, ..., z.

• iswalnum, ..., iswxdigit

  These C functions will only handle arguments in the range 0 to 127.

• The collate C functions strcoll, strxfrm, wcscoll, and wcsxfrm do not use the current locale set when they operate. The same applies to the C++ equivalent functionality.

• now

  This C++ function in the C++ header chrono uses the _Xtime_get_ticks() function and the C time.h macro CLOCKS_PER_SEC. By default, _Xtime_get_ticks() calls __clock(). If this is not applicable, you must override the setting of the macro _XTIME_NSECS_PER_TICK prior to using chrono or clock_t _Xtime_get_ticks().