C语言怎样计算天数

【程序1】：main(){intday,month,year,sum,leap;printf("\npleaseinputyear,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*/{case1:sum=0;break;case2:sum=31;break;case3:sum=59;break;case4:sum=90;break;case5:sum=120;break;case6:sum=151;break;case7:sum=181;break;case8:sum=212;break;case9:sum=243;break;case10:sum=273;break;case11:sum=304;break;case12:sum=334;break;default:printf("dataerror");break;}sum=sum+day;/*再加上某天的天数*/if(year%400==0||(year%4==0&&year%100!=0))/*判断是不是闰年*/leap=1;elseleap=0;if(leap==1&&month>2)/*如果是闰年且月份大于2,总天数应该加一天*/sum++;printf("Itisthe%dthday.",sum);}