I think it's better to make the days of week by enum . Like:
enum Days{
Monday = 1,
Tuesday,
Wednesday,
Thursday,
Friday
}
Then you get the day data by function like
void printDays(enum d,char * buffer)
{
const char *daysName[] = {"Monday","Tuesday","Wednesday","Thursday","Friday"};
memcpy(buffer,daysName[d-1]);
}
Then when you use
d[0].day is "Thursday"
d[1].day is "Monday"
d[2].day is "Wednesday"
It is easy sort .It in fact just store 1,2,3,4,5!