已知公元1年1月1日是星期一,计算输入的年月日是星期几?（用C语言编写）思路：计算出输入的年月日和公元1年1月1日距离多少天.计算公元1年到输入日期的上一年年底有多少天.再计算输入的年的1月到上月月底有多少天.再加上输入日期的天数.其中闰年满足：(year%4==0)&&(year%100!=0)||(year%400==0)

#include
main()
{
long year,month,day;
long totalday;
int week;
int monthday[12]={0,31,59,90,120,151,181,212,243,273,304,334};
int monthdayLeap[12]={0,31,60,91,121,152,182,213,244,274,305,335};
char * weekname[7]={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};
printf("Please input Year Month Day:");
scanf("%ld %ld %ld",&year,&month,&day);
totalday=(year-1)*365+(year-1)/4-(year-1)/100+(year-1)/400;
if((year%4==0)&&(year%100!=0)||(year%400==0))
totalday+=monthdayLeap[month-1];
else
totalday+=monthday[month-1];
totalday+=day;
week=totalday%7;
printf("%ld,%s\n",totalday,weekname[week]);
}
这里totalday的最后结果公元1年1月1日等于1.