// Zeller公式确定星期几，w=y+[y/4]+[c/4]-2c+[26(m+1)/10]+d-1
// y是年份取最后两位，c是世纪减1，m是月份，如果m是1月和2月，则m换成13和14，d是日期，[]表示取整，w除以7之后的余数就是星期几，如果余数为0，就是星期日
#include <stdio.h>
int main()
{
int year, month, y;
printf("请输入年：\n");
scanf("%d", &year);
if (year < 1900)
{
printf("年必须大于1900\n");
exit(-1);
}
y = year;
int c = y;
y %= 100;
c /= 100;
int m;
printf("请输入月：\n");
scanf("%d", &month);
if ((month < 0) || (month > 12))
{
printf("月在1--12之间\n");
exit(-1);
}
m = month;
if (1 == m)
{
m = 13;
}
if (2 == m)
{
m = 14;
}
int d;
printf("请输入日期：\n");
scanf("%d", &d);
if ((d < 0) || (d > 31))
{
printf("日期必须在1和31之间\n");
exit(-1);
}
int w =
y + (int)y / 4 + (int)c / 4 - 2 * c + (int)(26 * (m + 1) / 10) + d - 1;
w %= 7;
char r[20];
switch (w)
{
case 0:
sprintf(r,"%s","星期天");
break;
case 1:
sprintf(r,"%s","星期一");
break;
case 2:
sprintf(r,"%s","星期二");
break;
case 3:
sprintf(r,"%s","星期三");
break;
case 4:
sprintf(r,"%s","星期四");
break;
case 5:
sprintf(r,"%s","星期五");
break;
case 6:
sprintf(r,"%s","星期六");
break;
default:
exit(-1);
}
printf("\n%d-%d-%d：%s\n", year, month, d, r);
return 0;
}