c语言编程:输入年月日,求出该天是该年的第几天答:{intday,month,year,sum,leap;printf("\n请输入年、月、日,格式为:年,月,日(2015,12,10)\n");scanf("%d%d%d",&year,&month,&day);//格式为:20190510 switch(month)//先计算某月以前月份的总天数 {case1:sum=0;break;case2:sum=31;break;case3:sum=59;break;case4:sum=90;break;...