程序代码：

#include<stdio.h>
#include<stdlib.h>
int runnian(int year)
{
    if(year%4==0&&year%100!=0||year%400==0)
        return 1;
    else
        return 0;
}
int day1(int year,int month)
{
    int a[12]={31,28,31,30,31,30,31,31,30,31,30,31};
    if(runnian(year))
    a[1]=29;
    return a[month-1];
}
int day2(int year,int month,int day)
{
    int i,sum=0;
    for(i=1;i<month;i++)
    {
        sum+=day1(year,i);
    }
    sum+=day;
    return sum;
}
int week1(int year,int month,int day)
{
    int number=(year-1)+(year-1)/4-(year-1)/100+(year-1)/400+day2(year,month,day);
    number%=7;
    return number;

}
char *week2(int number)
{
    switch(number)
    {
        case 0:
        return "星期日";
        case 1:
        return "星期一";
        case 2:
        return "星期二";
        case 3:
        return "星期三";
        case 4:
        return "星期四";
        case 5:
        return "星期五";
        case 6:
        return "星期六";
        default:
            return "错误！请重新输入。";
               
    }
}
void x1(int year,int month,int day)
{
    int number=week1(year,month,day);
    if(runnian(year))
        printf("闰年");
    else
        printf("平年");
    printf("       %d    年         %d    月            %d     日%10s\n\n",year,month,day,week2(number));

}

int x3(int year,int month,int day)
{
    if(year<0||month<1||month>12||day<1||day>day1(year,month))
        return 0;
    else
        return 1;
}
void nianli(int year)
{
    int i;
    printf("\n");
    for(i=1;i<=12;i++)
    {
        if(runnian(year))
            printf("闰年");
        else
            printf("平年");
        printf(" %d 年 %d 月\n\n",year,i);
    }
}

void rili(int year,int month,int day)
{
    printf("\n");
    x1(year,month,day);
}
void main()
{
    int year,month,day,a,b;
    while(1)
    {
        printf("\n\n\n\n");
        printf("*****************************************************************\n\n");
        printf("                   *                      *                        \n");
        printf("                    欢迎进入万年历查询系统\n");
        printf("                   *                      *                        \n\n");
        printf("*****************************************************************\n\n\n");
        printf("                    1 年历 2 月历 3 日历 4 退出\n");
        printf("                    请输入您的选择《1~4》，按回车键确定：");
        scanf("%d,&b");
        switch(b)
        {
        case 1:
            printf("请输入您要查询的年份：");
            scanf("%d,&year");
            a=x3(year,1,1);
            if(a==0)
            {
                printf("错误！请您重新输入。\n");
                break;
            }
            nianli(year);
            break;
        case 2:
            printf("请输入您要查询的年和月，中间用空格隔开：");
            scanf("%d%d",&year,&month);
            a=x3(year,month,1);
            if(a==0)
            {
                printf("错误！请您重新输入。\n");
                break;
            }
            break;
        case 3:
            printf("请输入您要查询的年月日，中间用空格隔开：");
            scanf("%d%d%d",&year,&month,&day);
            a=x3(year,month,day);
            if(a==0)
            {
                printf("错误！请您重新输入。\n");
                break;
            }
            rili(year,month,day);
            break;
        case 4:
            exit(0);
        default:
            printf("错误！请您重新输入。\n\n");
            


        }




    }
}