日历C语言版

//变量定义没有完全按照C语言的语法规则来。
//文件命名为*.cpp后缀的即可, 不要命名成*.c的。

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <time.h>

//是否闰年
#define IS_LEAP_YEAR(iYear) (((iYear) % 100 == 0) ? ((iYear) % 400 == 0) : ((iYear) % 4 == 0))

int Calendar(int iYear, int iMonth);

int main()
{
	//获取今天的日期
	struct tm *today;
	time_t ltime;
	time(<ime);
	today = localtime(<ime);

//	printf("%d-%02d-%02d %02d:%02d:%02d\n星期%d 当年第%d天\n", 
//		today->tm_year + 1900, today->tm_mon + 1, today->tm_mday, 
//		today->tm_hour, today->tm_min, today->tm_sec, today->tm_wday, today->tm_yday);

	int iYear = today->tm_year + 1900;
	int iMonth = today->tm_mon + 1;

	do {
		system("cls");

		int ch = Calendar(iYear, iMonth);
		if (ch == 27) break;

		switch (ch)
		{
		case 75:	//<--
			iYear--;
			break;
		case 77:	//-->
			iYear++;
			break;
		case 80:	//下箭头
			iMonth++;
			if (iMonth > 12)
			{
				iYear++;
				iMonth = 1;
			}
			break;
		case 72:	//上箭头
			iMonth--;
			if (iMonth < 1)
			{
				iYear--;
				iMonth = 12;
			}
			break;
		case 71:	//Home
			iYear = today->tm_year + 1900;
			iMonth = today->tm_mon + 1;
			break;
		}
	} while (1);
}

//显示给定年月的日历
//返回值为获取的用户按键, 以确定下一步的操作
int Calendar(int iYear, int iMonth)
{
	int i, j, iDays;

	//初始化数组w的值为1至31
	int w[31];
	for (i = 0; i < 31; i++) w[i] = i+1;
	
	//获取本月天数于iDays中
	switch (iMonth)
	{
	case 1: case 3: case 5: case 7: case 8: case 10: case 12:
		iDays = 31;
		break;
	case 4: case 6: case 9: case 11:
		iDays = 30;
		break;
	case 2:
		iDays = IS_LEAP_YEAR(iYear) ? 29 : 28;
		break;
	}
	
	//显示 日历头
	printf("\n    %d年%d月 日历\n\n", iYear, iMonth);
	printf(" 日 一 二 三 四 五 六\n");
	printf("----------------------\n");
	

	//获取参数指定年月的第一天是周几。保存在firstday.tm_wday中
	struct tm firstday = {0};
	firstday.tm_year = iYear - 1900;
	firstday.tm_mon = iMonth - 1;
	firstday.tm_mday = 1;

	time_t ltime;
	ltime = mktime(&firstday);

	firstday = *localtime(<ime);

	//处理1号前的留空
	j = firstday.tm_wday;	//周几
	for (i = 0; i < j; i++)
	{
		printf("   ");	//3个空格
	}
	
	//显示日历正文
	for (i = 0; i < iDays; i++)
	{
		printf("%3d", w[i]);
		if (++j == 7)
		{
			printf("\n");//逢七换行
			j = 0;
		}
	}
	if (j != 0) printf("\n");


	//获取今天日期
	time(<ime);
	struct tm today = *localtime(<ime);

	//显示 日历尾
	printf("----------------------\n");
	printf("今天是: %d年%d月%d日\n\n", today.tm_year + 1900, today.tm_mon + 1, today.tm_mday);

	printf("←: 上一年  →: 下一年\n");
	printf("↑: 上一月  ↓: 下一月\n\n");
	printf("Home: 今天  Esc: 退出\n");

	//获取用户按键 (不用按回车立即返回)
	fflush(stdin);
	clearerr(stdin);

	int c = getch();
	if (c == 0xe0 || c == 0) c = getch();

	return c;
}