日历显示

功能实现：

1.输入一个年份，输出是在屏幕上显示该年的日历

2.输入年月，输出该月的日历。

3.输入年月日，输出距今天还有多少天，星期几，是否公历节

代码实现：

1.计算今天是星期几

int CaculateWeekDay(int y,int m, int d) {
    
	if(m==1||m==2) {
    
		m+=12;
		y--;
	}
	int iWeek=(d+2*m+3*(m+1)/5+y+y/4-y/100+y/400)%7; // 计算今天是星期机
	return iWeek;
}

2.计算天数

int to_day(int y, int m, int d) {
    
	int mon[] = {
    0,31,28,31,30,31,30,31,31,30,31,30,31};  // 月份影射表
	int day = 0;
	int i;
	for(i=1; i<y; i++) {
    
		day += (i%4==0 && i%100!=0 || i%400==0)? 366 : 365;
	}
	if(y%4==0 && y%100!=0 || y%400==0) mon[2]++;  // 计算结果
	for(i=1; i<m; i++) {
    
		day += mon[i];   // 计算
	}
	return day + d;

3.闰年判断

int isleapyear(int year) {
    
	if((year%4==0)&&(year%100!=0)||(year%400==0))
		return 1;
	else
		return 0;
}

3.获得每个月的天数

int monthday(int month,int year) {
    
	// 获取每个月的天数量
	switch(month) {
    
		case 1:
		case 3:
		case 5:
		case 7:
		case 8:
		case 10:
		case 12:
			return 31;
			break;

		case 4:
		case 6:
		case 9:
		case 11:
			return 30;
			break;

		case 2:
			if(isleapyear(year)) {
    
				return 29;//闰年29天
				break;
			} else {
    
				return 28;
				break;
			}

	}

}

4.主函数显示

int main() {
    
	time_t timep;
	struct tm *p;
	time(&timep);
	p=gmtime(&timep);
	char v[10];
	int year=0,month,days,weekday;
	int i,d,a,b,c,m=0,dt=0;
	while(1) {
    
		printf("please input the year:");
		scanf("%s",v);
		year = (v[0]-'0')*1000+(v[1]-'0')*100+(v[2]-'0')*10+(v[3]-'0');
		int l = strlen(v);
		if(l==6||l==7) {
     // i.e 2020.1 2020.12 length 6-7
			if(l==6) {
    
				m = v[5]-'0';
			}
			if(l==7) {
    
				m = (v[5]-'0')*10+(v[6]-'0');
			}
		} else if(l==8||l==9||l==10) {
      
			if(l==8) {
    
				m = v[5]-'0';
				dt= v[7];
			} else if(l==9) {
    
				if(v[6]=='.') {
    
					m = v[5]-'0';
					dt = (v[7]-'0')*10+(v[8]-'0');
				} else {
    
					m = (v[5]-'0')*10+(v[6]-'0');
					dt = (v[8]-'0');
				}
			} else {
    
				m = (v[5]-'0')*10+(v[6]-'0');
				dt = (v[8]-'0')*10+(v[9]-'0');
			}
		}
		days = year-1+(year-1)/400+(year-1)/4-(year-1)/100;
		if(m==0) {
    
			for(month=1; month<=12; month++) {
    
				printf("\t\t****%d年--%d月****\n",year,month);
				printf("sun\tmon\ttues\twed\tthur\tfir\tsat\t\n");//表头
				i = 1;
				d = 1;
				weekday = (days + 1)%7;  //求星期几
				while(i<=weekday) {
     //输出前面的空格
					printf("\t");
					i++;
				}

				while(d<=monthday(month,year)) {
       //输出日期
					weekday = (days + 1)%7;
					if(weekday==6)   //最后一个是星期六，输出之后要换行
						printf("%d\n",d);
					else             //不是星期六的输出后不换行
						printf("%d\t",d);
					if(d==monthday(month,year))
						printf("\n");
					d++;
					days++;
				}
			}
		} else {
    
			if(dt==0) {
    
				for(month=m; month<=m; month++) {
    
					printf("\t\t****%d年--%d月****\n",year,month);
					printf("sun\tmon\ttues\twed\tthur\tfir\tsat\t\n");//表头
					i = 1;
					d = 1;
					weekday = (days + 1)%7;  //求星期几
					while(i<=weekday) {
     //输出前面的空格
						printf("\t");
						i++;
					}
					while(d<=monthday(month,year)) {
       //输出日期
						weekday = (days + 1)%7;
						if(weekday==6)   //最后一个是星期六，输出之后要换行
							printf("%d\n",d);
						else             //不是星期六的输出后不换行
							printf("%d\t",d);
						if(d==monthday(month,year))
							printf("\n");
						d++;
						days++;
					}
				}
			} else {
    
				printf("距离今天:%d 星期%d 不是公立节日\n",diff(year,m,d,p->tm_year+1900,p->tm_mon+1,p->tm_mday),CaculateWeekDay(year,m,d)+1);
			}
		}
	}
}

5.完整程序

年历显示