c语言 输入对应的年月日，能判断对应是星期几，并且循环打印这一个月的日历表格

要求，输入对应的年月日，能判断对应是星期几，并且循环打印这一个月的日历表格
#include int main(int argc, const char * argv[]) {
int year,sum,sum1=0,sum2=0,sum3=0,month,a,sum4;
int year1,month1,day1;
printf("请输入年");
scanf("%d",&year1);
printf("请输入月");
scanf("%d",&month1);
printf("请输入日");
scanf("%d",&day1); if (year1<1900||month1>12||month1<=0||day1>31||day1<=0)
{
printf("输入错误\n");
return 0;
}
for (year=1900; year { if ((year%4==0&&year%100!=0)||(year%400==0))
{ sum1=sum1+366;
} else
sum1+=365;
}
for (month=1;month if (month==4||month==6||month==9||month==11) {
sum2+=30;
}
else if (month==2)
{ if (((year%4==0&&year%100!=0)||year%400==0))
{
sum2+=29;
} else {
sum2+=28;
}
}else {
sum2+=31;
}
}
sum3=day1;
sum=sum1+sum2+sum3;
sum4=sum1+sum2; switch (sum%7)
{ case 0:
{ printf("当前日期为星期天\n");
} break;
case 1:
{ printf("当前日期为星期一\n");
} break;
case 2:
{ printf("当前日期为星期二\n");
} break;
case 3:
{ printf("当前日期为星期三\n");
} break;
case 4:
{ printf("当前日期为星期四\n");
} break;
case 5:
{ printf("当前日期为星期五\n");
} break;
case 6:
{ printf("当前日期为星期六\n");
} break;
default:
printf("错误");
break; }
int i,j=1;
if (month1==4||month1==6||month1==9||month1==11) {
a=30;
}
else if (month==2)
{ if (((year%4==0&&year%100!=0)||year%400==0))
{
a=29;
}else {
a=28;
}
}else{
a=31;
}
printf("日\t一\t二\t三\t四\t五\t六\n");
while (j<=sum4%7+1) {
if(sum4%7+1==7)
break;
else
printf("\t");
j++;
}
for (i=1;i<=a;i++)
{
printf("%d\t",i);
if ((i+sum4)%7==6)
{
printf("\n");
}
} printf("\n");
return 0;
}