Create an array with at least a given number of bits
Yes, wrap it in a macro:

#ifdef CHAR_BIT
    #define BIT_PER_MIN_IN_DAY ((60 * 24 / CHAR_BIT) + (((60 * 24) % CHAR_BIT) ? 1 : 0))
#else
    #error "Platform not supported"
#endif

UCHAR minutesOfDay[BIT_PER_MIN_IN_DAY];