结构体\判断日期是否合法（代码分步解析）

#include
#include
#include

//检查日期函数_声明
int checkDate(Date date);

int main()
{
	int check=0;
	Date date;

	do
	{
		printf("请输入一个日期(格式为YYYY-MM-DD):\n");
		printf("位数不足不补零#\n");
		scanf("%d-%d-%d",&date.year ,&date.month,&date.day);
		check=checkDate(date);
	}while(check!=1);
	printf("日期正确！\n");

	system("pause");
	return 0;
}

定义一个结构体变量，存放日期 

typedef struct Date
{
	int year;
	int month;
	int day;
}Date;

然后定义一个判断日期合法性的函数 

//检查日期函数_定义
int checkDate(Date date)
{
	int check=0;
	
	//年份判断
	if(date.year<1900 || date.year>2100)
	{
		printf("年份错误！\n");
		return check;
	}

	//月份判断
	if(date.month<1 || date.month>12)
	{
		printf("月份错误！\n");
		return check;
	}

	int a=date.year;
	int m=date.month;
	//若为闰年，28天
	if ((a%4==0 && a%100!=0) || (a%400==0))
	{
		if(date.month==2 && date.day<=28 && date.day>=1)
		{
			printf("闰年日期错误！\n");
			return check;
		}
	}
	int judge=-1;
	//普通日期判断(1-31 0-30 -1-29)
	switch(m)
	{
	case 1:
		judge=1;
		break;
	case 2:
		judge=-1;
		break;
	case 3:
		judge=1;
		break;
	case 4:
		judge=0;
		break;
	case 5:
		judge=1;
		break;
	case 6:
		judge=0;
		break;
	case 7:
		judge=1;
		break;
	case 8:
		judge=1;
		break;
	case 9:
		judge=0;
		break;
	case 10:
		judge=1;
		break;
	case 11:
		judge=0;
		break;
	case 12:
		judge=1;
		break;
	}
	if((judge==1 && (date.day>31 || date.day<1)) || (judge==0 && (date.day>30 || date.day<1)) || (judge==-1 && (date.day>29 || date.day<1)))
	{
		printf("日期错误！\n");
		return check;
	}

	check=1;
	return check;
}