Question

我在stackoverflow中看到了这个错误消息问题，但它们都不是日期时间或日期类型，只能使用日期类型我已经创建了一个日期类型的类，并在日期类中为它写了一些重载。我的日期类是

using System;
namespace Common 
{
    public class Date
    {
        private DateTime _d1;

        public Date(DateTime dateTime)
        {
            _d1 = dateTime;
        }

        public static bool operator <(Date date1, Date date2)
        {
            bool flag = false;


            //Now, get the original DateTime Type of C#
            DateTime firstDate = Convert.ToDateTime(date1);
            DateTime secondDate = Convert.ToDateTime(date2);

            //Now compare the two DateTime variables and assign the flag to true 
            //if the first date is smaller than the second date
            int result = DateTime.Compare(firstDate, secondDate);
            if (result < 0)
            {
                flag = true;
            }
            return flag;
        }

        public static bool operator >(Date date1, Date date2)
        {
            bool flag = false;

            //Now, get the original DateTime Type of C#
            DateTime firstDate = Convert.ToDateTime(date1);
            DateTime secondDate = Convert.ToDateTime(date2);

            //Now compare the two DateTime variables and assign the flag to true 
            //if the first date is Greater than the second date
            int result = DateTime.Compare(firstDate, secondDate);
            if (result > 0)
            {
                flag = true;
            }
            return flag;
        }

        public static bool operator <=(Date date1, Date date2)
        {
            bool flag = false;

            //Now, get the original DateTime Type of C#
            DateTime firstDate = Convert.ToDateTime(date1);
            DateTime secondDate = Convert.ToDateTime(date2);

            //Now compare the two DateTime variables and assign the flag to true 
            //if the first date is Greater than the second date
            int result = DateTime.Compare(firstDate, secondDate);
            if (result <= 0)
            {
                flag = true;
            }

            return flag;
        }

        public static bool operator >=(Date date1, Date date2)
        {
            bool flag = false;

            //Now, get the original DateTime Type of C#
            DateTime firstDate = Convert.ToDateTime(date1);
            DateTime secondDate = Convert.ToDateTime(date2);

            //Now compare the two DateTime variables and assign the flag to true 
            //if the first date is Greater than the second date
            int result = DateTime.Compare(firstDate, secondDate);
            if (result >= 0)
            {
                flag = true;
            }
            return flag;
        }

        public static bool operator ==(Date date1, Date date2)
        {
            bool flag = false;

            //Now, get the original DateTime Type of C#
            DateTime firstDate = Convert.ToDateTime(date1);
            DateTime secondDate = Convert.ToDateTime(date2);

            //Now compare the two DateTime variables and assign the flag to true 
            //if the first date is Greater than the second date
            int result = DateTime.Compare(firstDate, secondDate);
            if (result == 0)
            {
                flag = true;
            }
            return flag;
        }

        public static bool operator !=(Date date1, Date date2)
        {
            bool flag = false;

            //Now, get the original DateTime Type of C#
            DateTime firstDate = Convert.ToDateTime(date1);
            DateTime secondDate = Convert.ToDateTime(date2);

            //Now compare the two DateTime variables and assign the flag to true 
            //if the first date is Greater than the second date
            int result = DateTime.Compare(firstDate, secondDate);
            if (result != 0)
            {
                flag = true;
            }
            return flag;
        }
    }//end of class Date
}//End of namespace

但问题是当我试图在我的代码页面后面使用它给我这个错误 - 无法将'Common.Date'类型的对象强制转换为'System.IConvertible

我正在使用它的代码 date purchaseDate = new Date（item.PurchaseDate）; 提交日期日期=新日期（item.SubmissionDate）;

                    if (purchaseDate>submissionSate)
                    {
                        //to do
                    }

此处在item对象中，purchaseate和submision日期是datetime属性，错误在if行中任何人都可以提供任何建议吗？这个问题的可能解决方案是什么？

Answer 1

您可以直接访问Date的字段。虽然我质疑这个Date对象的用处。

public static bool operator <(Date date1, Date date2)
{
    return date1 != null && date2 != null && date1._d1 < date2._d1
}

Answer 2

在>运算符重载中，您有

DateTime firstDate = Convert.ToDateTime(date1); 
DateTime secondDate = Convert.ToDateTime(date2);

并且Convert.ToDateTime没有超载会占用您的Date对象，因此您要调用Convert.ToDateTime(object)，这需要object来实施IConvertible。< / p>

您可以实施IConvertible，或者仅将_d1值与@ChaosPandion提及进行比较。

无法将“Common.Date”类型的对象强制转换为“System.IConvertible C＃”

2 个答案: