C语言实现的一个万年历小程序

#include<stdio.h>#define Mon   1#define Tues  2#define Wed   3#define Thur  4#define Fri   5#define Sat   6#define Sun   0#define January_days   31#define February_days   28#define March_days    31#define April_days    30#define May_days     31#define June_days     30#define July_days     31#define August_days    31#define September_days  30#define October_days   31#define November_days   30#define December_days   31#define first1month January_days#define first2month January_days+February_days#define first3month January_days+February_days+March_days#define first4month January_days+February_days+March_days+April_days#define first5month January_days+February_days+March_days+April_days+May_days#define first6month January_days+February_days+March_days+April_days+May_days+June_days#define first7month January_days+February_days+March_days+April_days+May_days+June_days /	         +July_days#define first8month January_days+February_days+March_days+April_days+May_days+June_days /	         +July_days+August_days#define first9month January_days+February_days+March_days+April_days+May_days+June_days /	         +July_days+August_days+September_days#define first10month January_days+February_days+March_days+April_days+May_days+June_days /	         +July_days+August_days+September_days+October_days#define first11month January_days+February_days+March_days+April_days+May_days+June_days /	         +July_days+August_days+September_days+October_days+November_daysint known_weekday = Tues;int known_year = 1901;int konwn_month = 1;int known_day = 1;int day_count(int month){		switch(month)	{		case 1: return 0;break;		case 2: return first1month;break;		case 3: return first2month;break;		case 4: return first3month;break;		case 5: return first4month;break;		case 6: return first5month;break;		case 7: return first6month;break;		case 8: return first7month;break;		case 9: return first8month;break;		case 10: return first9month;break;		case 11: return first10month;break;		case 12: return first11month;break;	}}/*char * month_name(int month){	switch(month)	{		case 1:			return "January";			break;		case 2:			return "February";			break;		case 3:			return "March";			break;		case 4:			return "April";			break;		case 5:			return "May";			break;		case 6:			return "June";			break;		case 7:			return "July";			break;		case 8:			return "August";			break;		case 9:			return "September";			break;		case 10:			return "October";			break;		case 11:			return "November";			break;		case 12:			return "December";			break;		default:			break;	}}*/char * month_name(int month){	switch(month)	{		case 1:			return "一月";			break;		case 2:			return "二月";			break;		case 3:			return "三月";			break;		case 4:			return "四月";			break;		case 5:			return "五月";			break;		case 6:			return "六月";			break;		case 7:			return "七月";			break;		case 8:			return "八月";			break;		case 9:			return "九月";			break;		case 10:			return "十月";			break;		case 11:			return "十一月";			break;		case 12:			return "十二月";			break;		default:			break;	}}/*按格式打印某年某月名称*/void first_line_print(int month, int year){	//printf("%20s %d /n",month_name(month),year);	printf("%8d年 %s /n",year, month_name(month));}/*按格式打印星期名称*/void week_print(){	//printf("%-6s%-6s%-6s%-6s%-6s%-6s%-6s/n","Sun.", "Mon.", "Tues.", "Wed.", "Thur.", "Fri.", "Sat.");	printf("%-3s%-3s%-3s%-3s%-3s%-3s%-3s/n","日", "一", "二", "三", "四", "五", "六");}/*计算该年该月份与已知日子之间的距离天数*/int date_distance_count(int month, int year){	int leap_year_count = 0;	int i;	int distance;	if (year > known_year)	{		for (i=known_year; i<year; i++)		{			if(((i%4 == 0) && (i%100 != 0) ) || (i%400 == 0))			{				leap_year_count++;					}		}		if (month > 2)		{			if(((year%4 == 0) && (year%100 != 0) ) || (year%400 == 0))			{				leap_year_count++;					}		}	}	else	if (year == known_year)	{		if (month > 2)		{			leap_year_count = 1;		}	}		distance = (year - known_year)*365 + leap_year_count + day_count(month);	return distance;	}/*确定该月份第一天是星期几*/int makesure_firstday_weekday(int month, int year){	int date_distance = 0;	int weekday;	date_distance = date_distance_count(month, year);	weekday = (known_weekday + date_distance)%7;	return weekday;	}/*依次打印出该月份的日子*/void print_in_turn(int month, int firstday, int year){	int i = 1;	int weekday;	switch(firstday)	{		case Sun:			break;		case Mon:			printf("%-3s","");			break;		case Tues:			printf("%-6s","");			break;		case Wed:			printf("%-9s","");			break;		case Thur:			printf("%-12s","");			break;		case Fri:			printf("%-15s","");			break;		case Sat:			printf("%-18s","");			break;	}	switch(month)	{		case 1:		case 3:		case 5:		case 7:		case 8:		case 10:		case 12:		{			for(i=0; i<31; i++)			{				weekday = (firstday + i)%7;				printf("%-3d",i+1);								if(weekday == Sat)				{					printf("/n");				}								}			break;		}		case 2:		{			if(((year%4 == 0) && (year%100 != 0) ) || (year%400 == 0)) /*闰年*/			{				for(i=0; i<29; i++)				{					weekday = (firstday + i)%7;					printf("%-3d",i+1);										if(weekday == Sat)					{						printf("/n");					}									}				break;			}			else /*平年*/			{				for(i=0; i<28; i++)				{					weekday = (firstday + i)%7;					printf("%-3d",i+1);										if(weekday == Sat)					{						printf("/n");					}									}				break;			}				}		case 4:		case 6:		case 9:		case 11:		{			for(i=0; i<30; i++)			{				weekday = (firstday + i)%7;/*计算该天是星期几*/				printf("%-3d",i+1);								if(weekday == Sat)				{					printf("/n");/*如果是星期六，则换行*/				}								}			break;		}				}}void date_print(int month, int year){	int firstday;	firstday = makesure_firstday_weekday(month, year);	print_in_turn(month, firstday, year);	printf("/n");}void main_month(int month, int year){	first_line_print(month, year);	week_print();	date_print(month, year);	printf("/n/n");}void main_calendar(int year){	int i;	for(i=1; i<=12; i++)	{		main_month(i, year);	}}int main(){	int year;	printf("请输入年份：year = ");	scanf("%d",&year);	printf("/n");	while(year < 1902)	{		printf("请输入大于1901的年份/n");		printf("请输入年份：year = ");		scanf("%d",&year);		printf("/n");	}		main_calendar(year);		scanf(" ");	return 0;}