I have noticed that VC11 returns different values for the AM/PM strings for non "C" / English locales than it did in VC10 and prior.
I believe this is a bug in the Microsoft C library.
strftime is required to null terminate the string it returns. The Microsoft implementatin does appear to be doing that however when a multibyte codepage is used it is returning the number of wide characters rather than the number of bytes copied.
If one ignores return value of strftime and instead looks at the individual characters returned to the output buffer the same characters are returned in VC 11 as in VC 10, it is just the return value of the number of characters that is incorrect.