namespace _2017_2_23判断日期格式优化代码
{
    class Program
    {
        static void Main(string[] args)
        {
            bool dateISOK = false;
            bool isRN = false;
            {
                int year; int month = 0; int day = 0;int num=0;
                Console.WriteLine("请输入年份：（1-9999）");
                year = Convert.ToInt32(Console.ReadLine());
                if (year >= 1 && year <= 9999)
                {
                    if (year >= 1 && year <= 9999 && year % 4 == 0 && year % 100 != 0 || year % 400 == 0) 
                    {
                        isRN = true;
                    }
                    Console.WriteLine("请输入月份：");
                    month = Convert.ToInt32(Console.ReadLine());
                    if (month >= 1 && month <= 12)
                    {
                        Console.WriteLine("请输入日期：");
                        day = Convert.ToInt32(Console.ReadLine());
                        if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12 && day >= 1 && day<= 31)
                        {
                            Console.WriteLine("您输入的日期格式正确");
                            dateISOK = true;
                        
                          
                        }

                        else if ((month == 4 || month == 6 || month == 9 || month == 11) && day >= 1 && day <= 30)
                        {
                            Console.WriteLine("您输入的日期格式正确");
                            dateISOK = true;
                        
                        }
                        else if (isRN==true && month == 2 && day >= 1 && day <= 29)
                        {
                            Console.WriteLine("您输入的日期格式正确");
                            dateISOK = true;
                            isRN = true;
                        
                        }
                        else if (isRN==false && month == 2 && day >= 1 && day <= 28)
                        {
                            Console.WriteLine("您输入的日期格式正确");
                            dateISOK = true;

                        
                        }


                        else
                        {
                            Console.WriteLine("您输入的日期格式不对");
                        }
                    }
                    else
                    {
                        Console.WriteLine("您输入的月份格式错误");
                    }
                }
                else
                {
                    Console.WriteLine("您输入的年份格式错了");
                }
                if(dateISOK==true&&month==1)
                {
                    num = day;
                }
                if(dateISOK==true&&month==2)
                {
                    num = 31 + day;
                }
                if(dateISOK==true&&month==3&&isRN==true)
                {
                    num = 31 + 29 + day;
                }
                if(dateISOK==true&&month==3&&isRN==false)
                {
                    num = 31 + 28 + day;
                }
                if (dateISOK == true && month == 4 && isRN == true)
                {
                    num = 31 + 29 +31+ day;
                }
                if (dateISOK == true && month == 4 && isRN == false)
                {
                    num = 31 + 28+31 + day;
                }
                if (dateISOK == true && month == 5 && isRN == true)
                {
                    num = 31 + 29 + 31 +30+ day;
                }
                if (dateISOK == true && month ==5 && isRN == false)
                {
                    num = 31 + 28 + 31 +30+ day;
                }
                if (dateISOK == true && month == 6 && isRN == true)
                {
                    num = 31 + 29 + 31 + 30+31 + day;
                }
                if (dateISOK == true && month ==6 && isRN == false)
                {
                    num = 31 + 28 + 31 + 30+31 + day;
                }
                if (dateISOK == true && month == 7 && isRN == true)
                {
                    num = 31 + 29 + 31 + 30 + 31+30 + day;
                }
                if (dateISOK == true && month == 7 && isRN == false)
                {
                    num = 31 + 28 + 31 + 30 + 31+30 + day;
                }
                if (dateISOK == true && month == 8 && isRN == true)
                {
                    num = 31 + 29 + 31 + 30 + 31 + 30 +31+ day;
                }
                if (dateISOK == true && month == 8 && isRN == false)
                {
                    num = 31 + 28 + 31 + 30 + 31 + 30+31 + day;
                }
                if (dateISOK == true && month == 9 && isRN == true)
                {
                    num = 31 + 29 + 31 + 30 + 31 + 30 + 31+31 + day;
                }
                if (dateISOK == true && month ==9&& isRN == false)
                {
                    num = 31 + 28 + 31 + 30 + 31 + 30 + 31 +31+ day;
                }
                if (dateISOK == true && month == 10 && isRN == true)
                {
                    num = 31 + 29 + 31 + 30 + 31 + 30 + 31 + 31+30 + day;
                }
                if (dateISOK == true && month == 10 && isRN == false)
                {
                    num = 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31+30 + day;
                }
                if (dateISOK == true && month == 11 && isRN == true)
                {
                    num = 31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 +31+ day;
                }
                if (dateISOK == true && month == 11 && isRN == false)
                {
                    num = 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 +31+ day;
                }
                if (dateISOK == true && month == 12 && isRN == true)
                {
                    num = 31 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 +30+ day;
                }
                if (dateISOK == true && month == 12&& isRN == false)
                {
                    num = 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 +30+ day;
                }
                 Console.WriteLine("你输入的日期是当年的第"+num+"天");
                Console.ReadLine();
            }

        }
    }
}