"Array" look-up table method (leap year)

一维数组 【以空间换时间】

define MONTHERROR -1
#define YEARERROR -2
#define DAYERROR -3
bool Leap_Year(int year)
{
    
	bool res = false;
	if ((year % 100 != 0 && year % 4 == 0) || year % 400 == 0)
	{
    
		res = true;
	}
	return res;
}
int Get_YM_Day(int year, int month)
{
    
//空间换时间 static Let their survival period longer,在数据区,const Let it do not change,Ability to get smaller.
//查表法
	static const  int days[] = {
     29,31,28,31,30,31,30,31,31,30,31,30,31 };
	if (month == 2 && Leap_Year(year))
	{
    
		month = 0;
	}
	return days[month];
}
int Get_YMD_Total(int year, int month, int day)
{
    
	int sum = 0;
// int da = 0;
	//查表法：static const int sum[] = {0, 0 , 31,59,90,120,151,181,212,243,273,304,334,365};
  // 0 1 2 3 4 5 6 7 8 9 10 11 12 13
  //The total number of days are the current digital and input the number of days.
	if (year < 1) return YEARERROR;
	if (month < 1 || month>12) return MONTHERROR;
	if (day<1 || day>Get_YM_Day(year, month)) return DAYERROR;
/* if (month>2&& Leap_Year(year,month)) { //如果月份大于2 ,So to judge whether a leap year,如果小于2就没必要了 da =1; */	}
	for (int i = 0; i < month; i++)
	{
    
		sum = sum + Get_YM_Day(year, i);
	}
	return sum + day;
// return sum + day + da ;
 }
int main()
{
    
	int year = 0, month = 0, day = 0;
	scanf_s("%d/%d/%d", &year, &month, &day);
	int n = Get_YMD_Total(year, month, day);
	printf("%d/%d/%d=>total: %d\n", year, month, day, n);
	// Crossing the line and input wrong judgment
	switch (n)
	{
    
	case YEARERROR:
		printf("year input error %d\n", year);
		break;
	case MONTHERROR:
		printf("month input error %d\n",month);
		break;
	case DAYERROR:
		printf("day input error %d\n", day);
		break;
	default:
		printf("%d year %d month %d day\n", year,month,day);
		break;
	}
	return 0;
}