程序代码：

#include<stdio.h>

int main()
{printf("  万年历by\n");
void abc( int year,int month);
int year,month;
for(;;)
{printf("请输入要查询的年份和月份\n");
printf("年份:");
scanf("%d",&year);
printf("月份:");
scanf("%d");
for(;;)
if(year>0&&(1<=month&&month<=12))break;
else{printf("请输入正确的年份和月份");
printf("年份:");
scanf("%d\n",&year);
printf("月份:");
scanf("%d\n");}
abc(year,month);
return 0;
}
}


void abc(int year,int month)
{int preyear;int premonth;int predays;int days; int leap;int i;
preyear=year-1;
premonth=month-1;
leap=((year%4&&year%100!=0)||(year%400==0))?1:0;
predays=preyear*365+preyear/4+preyear/400-preyear/100;
switch(premonth)
{case 1:predays+=31;break;

 case 2:predays+=59;break;

 case 3:predays+=90;break;

 case 4:predays+=120;break;

 case 5:predays+=151;break;

 case 6:predays+=181;break;

 case 7:predays+=212;break;

 case 8:predays+=243;break;

 case 9:predays+=273;break;

 case 10:predays+=304;break;

 case 11:predays+=334;break;

 
}
if(leap&&month>=3)predays++;
switch(month)
{case 1:days=31;printf("1月 ");break;

 case 2:days=29;printf("2月 ");break;

 case 3:days=31;printf("3月 ");break;

 case 4:days=30;printf("4月 ");break;

 case 5:days=31;printf("5月 ");break;

 case 6:days=30;printf("6月 ");break;

 case 7:days=31;printf("7月 ");break;

 case 8:days=31;printf("8月 ");break;

 case 9:days=30;printf("9月 ");break;

 case 10:days=31;printf("10月 ");break;

 case 11:days=30;printf("11月 ");break;

 case 12:days=31;printf("12月 ");break;
}
if(leap&&month==2)days=28;
printf("%d",year);
if(leap)printf("闰年\n");
printf("日 一 二 三 四 五 六\n");
predays%=7;
for(i=1;i<=predays;i++)
printf(" ");
for(i=1;i<=days;i++)
{printf("%2d",i);
if((i+predays)%7==6)printf("\n");
}
printf("\n");
}