...一年的第几天,同时判断这一天是星期几。(用switch语句)答:*/#include<stdio.h>int main(){ int day, month, year, sum, leap; printf("\nplease input year,month,day\n"); scanf("%d%d%d",&year,&month,&day); switch(month){ //先计算某月以前月份的总天数 case 1:sum = 0;break; case 2:sum = 31;break; c...