main()
{
     int y,m,d,w,c,i=1;
     printf("year   ");     scanf("%d",&y);
     printf("month ");     scanf("%d",&m);
     printf("day    ");     scanf("%d",&d);
     while(i==1)
     {
         if    (      (y%4!=0&&m>0&&m!=2&&m<13&&d>0&&d<32)
                  ||(y%4!=0&&m==2&&d>0&&d<29)
                  ||(y%4==0&&m>0&&m!=2&&m<13&&d>0&&d<32)
                  ||(y%4==0&&m==2&&d>0&&d<30)                )
         {
             c=y/100;
             y=y-100*c;
             if (m<3)
             {
             y=y-1;
             m=m+12;
             }
             w=y+y/4;
             w=w+c/4;
             w=w-2*c+26*(m+1)/10+d-1;
             w=w%7;
             switch(w)
             {
              case 0:printf("Sunday");break;
              case 1:printf("Monday");break;
              case 2:printf("Tuesday");break;
              case 3:printf("Wednesday");break;
              case 4:printf("Thursday");break;
              case 5:printf("Friday");break;
              default:printf("Saturday");
             }
         }
         else
         {
         printf("error \n \n");
         }
     printf("\n\nyear   ");     scanf("%d",&y);
     printf("month ");     scanf("%d",&m);
     printf("day    ");     scanf("%d",&d);
     }
     getch();
}
刚才做的程序