преобразовать дату и время в строку (convert date and time to a string)
Возвращаемое значение (Return value)
If the total number of resulting bytes including the terminating
null byte is not more than maxsize, these functions shall return
the number of bytes placed into the array pointed to by s, not
including the terminating NUL character. Otherwise, 0 shall be
returned and the contents of the array are unspecified.
