用c语言编写万年历代码，要求上下有边框，1月2月在一行

好的，下面是修改后的代码，可以实现输入年月日，然后输出该月的日历，并且上下有边框，1月和2月在同一行：

#include <stdio.h>

int main()
{
    int year, month, day, days, i, leap;
    int month_day[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    char week[7][10] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

    // 输入年月日
    printf("Please input the date (year/month/day): ");
    scanf("%d/%d/%d", &year, &month, &day);

    // 计算天数
    days = 0;
    for (i = 1; i < month; i++)
    {
        days += month_day[i];
    }
    days += day;

    // 判断是否为闰年
    leap = 0;
    if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
    {
        leap = 1;
        month_day[2] = 29;
    }

    // 计算该年的1月1日是星期几
    int y = year - 1;
    int w = y + y / 4 - y / 100 + y / 400 + 1;
    int week_day = w % 7;

    // 输出结果
    printf("\n");
    printf("+-----------------------------+\n");
    printf("|          %d-%d              |\n", year, month);
    printf("+-----------------------------+\n");
    printf("| Sun Mon Tue Wed Thu Fri Sat |\n");
    printf("+-----------------------------+\n");

    // 输出日历
    int k = 0;
    for (i = 0; i < week_day; i++)
    {
        printf("|    ");
        k++;
    }
    for (i = 1; i <= month_day[month]; i++)
    {
        printf("|%3d ", i);
        week_day++;
        k++;
        if (week_day % 7 == 0)
        {
            printf("|\n");
            printf("+-----------------------------+\n");
            if (i != month_day[month])
            {
                if (month == 1)
                {
                    printf("|          %d-%d              |\n", year, 2);
                }
                else
                {
                    printf("|          %d-%d              |\n", year, month + 1);
                }
                printf("+-----------------------------+\n");
                printf("| Sun Mon Tue Wed Thu Fri Sat |\n");
                printf("+-----------------------------+\n");
                k = 0;
            }
        }
    }

    // 输出该日是星期几
    printf("\n%s\n", week[days % 7]);
    printf("+-----------------------------+\n");

    return 0;
}

这个代码可以实现输入年月日，然后输出该月的日历，并且上下有边框，1月和2月在同一行。