typedef struct {
char* sun;
char* mon;
char* tue;
char* wed;
char* th;
char* fri;
char* sat;
}TABLE;

TABLE t = {"月曜日","火曜日","水曜日","木曜日","金曜日","土曜日"};
/* dayに0-6が入ってる */

char* p;
p = (char*)&t + (day*sizeof(char*))
printf("%s"p);