c语言结构体应用例程：输入今天日期，输出明天日期

#include
#include

struct date {
	int day;
	int month;
	int year;
};

bool isleap ( struct date d ){//是闰年返回true
	bool leap = false;
	if ((d.year%4 == 0 && d.year%100 != 0) || d.year%100 == 0)
		leap = true;
	return leap;              //单一出口原则
}

int daysofmonth ( struct date d ){//判断每月天数
	int days;
	const int dayspermonth[12] = {31,28,31,30,31,30,31,31,30,31,30,31};
	if ( d.month == 2 && isleap(d) )
		days = 29;
	else
		days = dayspermonth[d.month-1];
	return days;    //注意函数的返回值不能丢
}
int main ( int argc, char const *argv[])
{
	struct date today, tomorrow;
	printf("请输入今天的日期(mm dd yy):\n");
	scanf("%d %d %d",&today.month,&today.day,&today.year);
	//注意%d用什么隔开，输入时就用什么隔开
	if( today.day<1 || today.day>31 || today.month<1 ||today.month>12 )
		printf("输入有误！！\n");
		return 0;  //此处瑕疵，没有单一出口，暂不知如何直接结束程序
	if( today.day != daysofmonth(today) ){
		tomorrow.day = today.day + 1;
		tomorrow.month = today.month;
		tomorrow.year = today.year;
	}else if( today.month == 12 ){
		tomorrow.day = 1;
		tomorrow.month = 1;
		tomorrow.year = today.year+1;
	}else{
		tomorrow.day = 1;
		tomorrow.month = today.month + 1; 
		tomorrow.year = today.year;
	}
	printf( "明天的日期是%d-%d-%d",tomorrow.month,tomorrow.day,tomorrow.year);
	
	return 0;
}