聊一聊c#中的MATH.ROUND方法

MATH.ROUND方法微软的官方解释是：将值舍入到最接近的整数或指定的小数位数。

该方法有如下8个重载：

        /// <summary>
        /// 将小数值舍入到最接近的整数值。
        /// </summary>
        /// <param name="d">要舍入的小数。</param>
        /// <returns>最接近参数 d 的整数。如果 d 的小数部分正好处于两个整数中间，其中一个整数为偶数，另一个整数为奇数，则返回偶数。请注意，此方法返回 System.Decimal，而不是整数类型。</returns>
        decimal Round(decimal d);
        /// <summary>
        /// 将双精度浮点值舍入为最接近的整数值。
        /// </summary>
        /// <param name="a">要舍入的双精度浮点数。</param>
        /// <returns>最接近 a 的整数。如果 a 的小数部分正好处于两个整数中间，其中一个整数为偶数，另一个整数为奇数，则返回偶数。请注意，此方法返回 System.Double，而不是整数类型。</returns>
        double Round(double a);
        /// <summary>
        ///  将小数值舍入到最接近的整数。一个参数，指定当一个值正好处于两个数中间时如何舍入这个值。
        /// </summary>
        /// <param name="d">要舍入的小数。</param>
        /// <param name="mode">在两个数字之间时如何舍入 d 的规范。</param>
        /// <returns>最接近 d 的整数。如果 d 是两个数字的中值，这两个数字一个为偶数，另一个为奇数，则 mode 确定返回两个数字中的哪一个。</returns>
        decimal Round(decimal d, MidpointRounding mode);
        /// <summary>
        /// 将小数值按指定的小数位数舍入。
        /// </summary>
        /// <param name="d">要舍入的小数。</param>
        /// <param name="decimals">返回值中的小数位数。</param>
        /// <returns>最接近 d 的 decimals 位小数的数字。</returns>
        decimal Round(decimal d, int decimals);
        /// <summary>
        /// 将双精度浮点值舍入为最接近的整数。一个参数，指定当一个值正好处于两个数中间时如何舍入这个值。
        /// </summary>
        /// <param name="value">要舍入的双精度浮点数。</param>
        /// <param name="mode">在两个数字之间时如何舍入 value 的规范。</param>
        /// <returns>最接近 value 的整数。如果 value 是两个整数的中值，这两个整数一个为偶数，另一个为奇数，则 mode 确定返回两个整数中的哪一个。</returns>
        double Round(double value, MidpointRounding mode);
        /// <summary>
        /// 将双精度浮点值按指定的小数位数舍入。
        /// </summary>
        /// <param name="value">要舍入的双精度浮点数。</param>
        /// <param name="digits">返回值中的小数数字。</param>
        /// <returns></returns>
        double Round(double value, int digits);
        /// <summary>
        /// 将双精度浮点值按指定的小数位数舍入。一个参数，指定当一个值正好处于两个数中间时如何舍入这个值。
        /// </summary>
        /// <param name="value">要舍入的双精度浮点数。</param>
        /// <param name="digits">返回值中的小数数字。</param>
        /// <param name="mode">在两个数字之间时如何舍入 value 的规范。</param>
        /// <returns>最接近 value 的 digits 位小数的数字。如果 value 比 digits 少部分数字，value 原样返回。</returns>
        double Round(double value, int digits, MidpointRounding mode);
        /// <summary>
        /// 将小数值按指定的小数位数舍入。一个参数，指定当一个值正好处于两个数中间时如何舍入这个值。
        /// </summary>
        /// <param name="d">要舍入的小数。</param>
        /// <param name="decimals">返回值中的小数位数。</param>
        /// <param name="mode">在两个数字之间时如何舍入 d 的规范。</param>
        /// <returns>最接近 d 的 decimals 位小数的数字。如果 d 比 decimals 少部分数字，d 原样返回。</returns>
        decimal Round(decimal d, int decimals, MidpointRounding mode);

其中参数MidpointRounding是个枚举，对应的值为：

 现将各个重载方法一一实现如下：

1、得到整数

　　1.1、double Round(double a)输出结果为：

　　

 　　1.2、decimal Round(decimal d)输出结果为：

　　

 　　1.3、decimal Round(decimal d, int decimals)输出结果为：

　　

 　　1.4、double Round(double value, int digits)输出结果为：

　　

 　　1.5、decimal Round(decimal d, MidpointRounding mode)输出结果为：

　　

 　　1.6、double Round(double value, MidpointRounding mode)输出结果：

　　

 　　1.7、double Round(double value, int digits, MidpointRounding mode)输出结果：

　　

 　　1.8、decimal Round(decimal d, int decimals, MidpointRounding mode)输出结果：

　　

 2、得到两位小数

　　2.1、decimal Round(decimal d, int decimals)输出结果：

　　

 　　2.2、double Round(double value, int digits)输出结果：

　　

 　　2.3、double Round(double value, int digits, MidpointRounding mode)输出结果：

　　

 　　2.4、decimal Round(decimal d, int decimals, MidpointRounding mode)输出结果：

　　

 根据以上运行结果，我们在使用Round处理数据时，不能随便使用，要根据自己的具体需求来选择对应的方法，特别是我们对数据进行四舍五入时，要选对适合自己项目需要的方法是很重要的。如果随意使用，可能得到意想不到的结果。

　　可运行控制台代码：

#region 整数
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*********************************整数输出*********************************");
            Console.ForegroundColor = ConsoleColor.Red;
            //double Round(double a);
            Console.WriteLine($"Math.Round(0.4)输出结果：{Math.Round(0.4)}");
            Console.WriteLine($"Math.Round(0.5)输出结果：{Math.Round(0.5)}");
            Console.WriteLine($"Math.Round(0.501)输出结果：{Math.Round(0.501)}");
            Console.WriteLine($"Math.Round(0.6)输出结果：{Math.Round(0.6)}");
            Console.WriteLine($"Math.Round(1.5)输出结果：{Math.Round(1.5)}");
            Console.WriteLine($"Math.Round(2.5)输出结果：{Math.Round(2.5)}");
            Console.WriteLine($"Math.Round(3.5)输出结果：{Math.Round(3.5)}");
            Console.WriteLine($"Math.Round(4.5)输出结果：{Math.Round(4.5)}");
            Console.WriteLine($"Math.Round(5.5)输出结果：{Math.Round(5.5)}");
            Console.WriteLine($"Math.Round(6.5)输出结果：{Math.Round(6.5)}");
            Console.WriteLine($"Math.Round(7.5)输出结果：{Math.Round(7.5)}");
            Console.WriteLine($"Math.Round(8.5)输出结果：{Math.Round(8.5)}");
            Console.WriteLine($"Math.Round(9.5)输出结果：{Math.Round(9.5)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("***************Math.Round(double)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;
            //decimal Round(decimal d);
            Console.WriteLine($"Math.Round((decimal)0.4)输出结果：{Math.Round((decimal)0.4)}");
            Console.WriteLine($"Math.Round((decimal)0.5)输出结果：{Math.Round((decimal)0.5)}");
            Console.WriteLine($"Math.Round((decimal)0.501)输出结果：{Math.Round((decimal)0.501)}");
            Console.WriteLine($"Math.Round((decimal)0.6)输出结果：{Math.Round((decimal)0.6)}");
            Console.WriteLine($"Math.Round((decimal)1.5)输出结果：{Math.Round((decimal)1.5)}");
            Console.WriteLine($"Math.Round((decimal)2.5)输出结果：{Math.Round((decimal)2.5)}");
            Console.WriteLine($"Math.Round((decimal)3.5)输出结果：{Math.Round((decimal)3.5)}");
            Console.WriteLine($"Math.Round((decimal)4.5)输出结果：{Math.Round((decimal)4.5)}");
            Console.WriteLine($"Math.Round((decimal)5.5)输出结果：{Math.Round((decimal)5.5)}");
            Console.WriteLine($"Math.Round((decimal)6.5)输出结果：{Math.Round((decimal)6.5)}");
            Console.WriteLine($"Math.Round((decimal)7.5)输出结果：{Math.Round((decimal)7.5)}");
            Console.WriteLine($"Math.Round((decimal)8.5)输出结果：{Math.Round((decimal)8.5)}");
            Console.WriteLine($"Math.Round((decimal)9.5)输出结果：{Math.Round((decimal)9.5)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("**************Math.Round(decimal)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;

            //decimal Round(decimal d, int decimals);
            Console.WriteLine($"Math.Round((decimal)0.4,0)输出结果：{Math.Round((decimal)0.4, 0)}");
            Console.WriteLine($"Math.Round((decimal)0.5, 0)输出结果：{Math.Round((decimal)0.5, 0)}");
            Console.WriteLine($"Math.Round((decimal)0.501, 0)输出结果：{Math.Round((decimal)0.501, 0)}");
            Console.WriteLine($"Math.Round((decimal)0.6, 0)输出结果：{Math.Round((decimal)0.6, 0)}");
            Console.WriteLine($"Math.Round((decimal)1.5, 0)输出结果：{Math.Round((decimal)1.5, 0)}");
            Console.WriteLine($"Math.Round((decimal)2.5, 0)输出结果：{Math.Round((decimal)2.5, 0)}");
            Console.WriteLine($"Math.Round((decimal)3.5, 0)输出结果：{Math.Round((decimal)3.5, 0)}");
            Console.WriteLine($"Math.Round((decimal)4.5, 0)输出结果：{Math.Round((decimal)4.5, 0)}");
            Console.WriteLine($"Math.Round((decimal)5.5, 0)输出结果：{Math.Round((decimal)5.5, 0)}");
            Console.WriteLine($"Math.Round((decimal)6.5, 0)输出结果：{Math.Round((decimal)6.5, 0)}");
            Console.WriteLine($"Math.Round((decimal)7.5, 0)输出结果：{Math.Round((decimal)7.5, 0)}");
            Console.WriteLine($"Math.Round((decimal)8.5, 0)输出结果：{Math.Round((decimal)8.5, 0)}");
            Console.WriteLine($"Math.Round((decimal)9.5, 0)输出结果：{Math.Round((decimal)9.5, 0)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("**************Math.Round(decimal,int)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;
            //double Round(double value, int digits);
            Console.WriteLine($"Math.Round(0.4,0)输出结果：{Math.Round(0.4, 0)}");
            Console.WriteLine($"Math.Round(0.5, 0)输出结果：{Math.Round(0.5, 0)}");
            Console.WriteLine($"Math.Round(0.501, 0)输出结果：{Math.Round(0.501, 0)}");
            Console.WriteLine($"Math.Round(0.6, 0)输出结果：{Math.Round(0.6, 0)}");
            Console.WriteLine($"Math.Round(1.5, 0)输出结果：{Math.Round(1.5, 0)}");
            Console.WriteLine($"Math.Round(2.5, 0)输出结果：{Math.Round(2.5, 0)}");
            Console.WriteLine($"Math.Round(3.5, 0)输出结果：{Math.Round(3.5, 0)}");
            Console.WriteLine($"Math.Round(4.5, 0)输出结果：{Math.Round(4.5, 0)}");
            Console.WriteLine($"Math.Round(5.5, 0)输出结果：{Math.Round(5.5, 0)}");
            Console.WriteLine($"Math.Round(6.5, 0)输出结果：{Math.Round(6.5, 0)}");
            Console.WriteLine($"Math.Round(7.5, 0)输出结果：{Math.Round(7.5, 0)}");
            Console.WriteLine($"Math.Round(8.5, 0)输出结果：{Math.Round(8.5, 0)}");
            Console.WriteLine($"Math.Round(9.5, 0)输出结果：{Math.Round(9.5, 0)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("**************Math.Round(double,int)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;

            //decimal Round(decimal d, MidpointRounding mode);
            Console.WriteLine($"Math.Round((decimal)0.4, MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.4, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)0.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)0.501,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.501, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)0.6,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.6, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)1.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)1.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)2.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)2.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)3.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)3.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)4.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)4.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)5.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)5.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)6.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)6.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)7.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)7.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)8.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)8.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)9.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)9.5, MidpointRounding.AwayFromZero)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(decimal,MidpointRounding.AwayFromZero)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine($"Math.Round((decimal)0.4, MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.4, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)0.5,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)0.501,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.501, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)0.6,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.6, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)1.5,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)1.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)2.5,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)2.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)3.5,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)3.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)4.5,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)4.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)5.5,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)5.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)6.5,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)6.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)7.5,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)7.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)8.5,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)8.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)9.5,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)9.5, MidpointRounding.ToEven)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(decimal,MidpointRounding.ToEven)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;


            //double Round(double value, MidpointRounding mode);
            Console.WriteLine($"Math.Round(0.4, MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.4, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(0.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(0.501,MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.501, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(0.6,MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.6, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(1.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round(1.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(2.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round(2.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(3.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round(3.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(4.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round(4.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(5.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round(5.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(6.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round(6.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(7.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round(7.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(8.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round(8.5, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(9.5,MidpointRounding.AwayFromZero)输出结果：{Math.Round(9.5, MidpointRounding.AwayFromZero)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(double,MidpointRounding.AwayFromZero)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine($"Math.Round(0.4, MidpointRounding.ToEven)输出结果：{Math.Round(0.4, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(0.5,MidpointRounding.ToEven)输出结果：{Math.Round(0.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(0.501,MidpointRounding.ToEven)输出结果：{Math.Round(0.501, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(0.6,MidpointRounding.ToEven)输出结果：{Math.Round(0.6, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(1.5,MidpointRounding.ToEven)输出结果：{Math.Round(1.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(2.5,MidpointRounding.ToEven)输出结果：{Math.Round(2.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(3.5,MidpointRounding.ToEven)输出结果：{Math.Round(3.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(4.5,MidpointRounding.ToEven)输出结果：{Math.Round(4.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(5.5,MidpointRounding.ToEven)输出结果：{Math.Round(5.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(6.5,MidpointRounding.ToEven)输出结果：{Math.Round(6.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(7.5,MidpointRounding.ToEven)输出结果：{Math.Round(7.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(8.5,MidpointRounding.ToEven)输出结果：{Math.Round(8.5, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(9.5,MidpointRounding.ToEven)输出结果：{Math.Round(9.5, MidpointRounding.ToEven)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(double,MidpointRounding.ToEven)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;

            //double Round(double value, int digits, MidpointRounding mode);
            Console.WriteLine($"Math.Round(0.4,0, MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.4, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(0.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(0.501,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.501, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(0.6,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.6, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(1.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(1.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(2.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(2.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(3.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(3.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(4.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(4.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(5.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(5.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(6.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(6.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(7.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(7.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(8.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(8.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(9.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round(9.5, 0, MidpointRounding.AwayFromZero)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(double,int,MidpointRounding.AwayFromZero)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine($"Math.Round(0.4,0, MidpointRounding.ToEven)输出结果：{Math.Round(0.4, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(0.5,0,MidpointRounding.ToEven)输出结果：{Math.Round(0.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(0.501,0,MidpointRounding.ToEven)输出结果：{Math.Round(0.501, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(0.6,0,MidpointRounding.ToEven)输出结果：{Math.Round(0.6, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(1.5,0,MidpointRounding.ToEven)输出结果：{Math.Round(1.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(2.5,0,MidpointRounding.ToEven)输出结果：{Math.Round(2.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(3.5,0,MidpointRounding.ToEven)输出结果：{Math.Round(3.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(4.5,0,MidpointRounding.ToEven)输出结果：{Math.Round(4.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(5.5,0,MidpointRounding.ToEven)输出结果：{Math.Round(5.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(6.5,0,MidpointRounding.ToEven)输出结果：{Math.Round(6.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(7.5,0,MidpointRounding.ToEven)输出结果：{Math.Round(7.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(8.5,0,MidpointRounding.ToEven)输出结果：{Math.Round(8.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(9.5,0,MidpointRounding.ToEven)输出结果：{Math.Round(9.5, 0, MidpointRounding.ToEven)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(double,int,MidpointRounding.ToEven)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;

            //decimal Round(decimal d, int decimals, MidpointRounding mode);
            Console.WriteLine($"Math.Round((decimal)0.4,0, MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.4, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)0.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)0.501,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.501, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)0.6,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.6, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)1.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)1.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)2.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)2.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)3.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)3.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)4.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)4.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)5.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)5.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)6.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)6.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)7.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)7.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)8.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)8.5, 0, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)9.5,0,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)9.5, 0, MidpointRounding.AwayFromZero)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(decimal,int,MidpointRounding.AwayFromZero)*END***************");
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine($"Math.Round((decimal)0.4,0, MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.4, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)0.5,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)0.501,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.501, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)0.6,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.6, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)1.5,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)1.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)2.5,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)2.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)3.5,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)3.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)4.5,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)4.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)5.5,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)5.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)6.5,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)6.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)7.5,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)7.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)8.5,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)8.5, 0, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)9.5,0,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)9.5, 0, MidpointRounding.ToEven)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(decimal,int,MidpointRounding.ToEven)*END*********************");


            #endregion

            #region 两位小数
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*********************************两位小数*********************************");
            Console.ForegroundColor = ConsoleColor.Red;
            //decimal Round(decimal d, int decimals);
            Console.WriteLine($"Math.Round((decimal)0.464,2)输出结果：{Math.Round((decimal)0.464, 2)}");
            Console.WriteLine($"Math.Round((decimal)0.465, 2)输出结果：{Math.Round((decimal)0.465, 2)}");
            Console.WriteLine($"Math.Round((decimal)0.46501, 2)输出结果：{Math.Round((decimal)0.46501, 2)}");
            Console.WriteLine($"Math.Round((decimal)0.466, 2)输出结果：{Math.Round((decimal)0.466, 2)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("**************Math.Round(decimal,int)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;
            //double Round(double value, int digits);
            Console.WriteLine($"Math.Round(0.464,2)输出结果：{Math.Round(0.464, 2)}");
            Console.WriteLine($"Math.Round(0.465, 2)输出结果：{Math.Round(0.465, 2)}");
            Console.WriteLine($"Math.Round(0.46501, 2)输出结果：{Math.Round(0.46501, 2)}");
            Console.WriteLine($"Math.Round(0.466, 2)输出结果：{Math.Round(0.466, 2)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("**************Math.Round(double,int)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;

            //double Round(double value, int digits, MidpointRounding mode);
            Console.WriteLine($"Math.Round(0.464,2, MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.464, 2, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(0.465,2,MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.465, 2, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(0.46501,2,MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.46501, 2, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round(0.466,2,MidpointRounding.AwayFromZero)输出结果：{Math.Round(0.466, 2, MidpointRounding.AwayFromZero)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(double,int,MidpointRounding.AwayFromZero)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine($"Math.Round(0.464,2, MidpointRounding.ToEven)输出结果：{Math.Round(0.464, 2, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(0.465,2,MidpointRounding.ToEven)输出结果：{Math.Round(0.465, 2, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(0.46501,2,MidpointRounding.ToEven)输出结果：{Math.Round(0.46501, 2, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round(0.466,2,MidpointRounding.ToEven)输出结果：{Math.Round(0.466, 2, MidpointRounding.ToEven)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(double,int,MidpointRounding.ToEven)*END*********************");
            Console.ForegroundColor = ConsoleColor.Red;

            //decimal Round(decimal d, int decimals, MidpointRounding mode);
            Console.WriteLine($"Math.Round((decimal)0.464,2, MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.464, 2, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)0.465,2,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.465, 2, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)0.46501,2,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.46501, 2, MidpointRounding.AwayFromZero)}");
            Console.WriteLine($"Math.Round((decimal)0.466,2,MidpointRounding.AwayFromZero)输出结果：{Math.Round((decimal)0.466, 2, MidpointRounding.AwayFromZero)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(decimal,int,MidpointRounding.AwayFromZero)*END***************");
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine($"Math.Round((decimal)0.464,2, MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.464, 2, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)0.465,2,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.465, 2, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)0.46501,2,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.46501, 2, MidpointRounding.ToEven)}");
            Console.WriteLine($"Math.Round((decimal)0.466,2,MidpointRounding.ToEven)输出结果：{Math.Round((decimal)0.466, 2, MidpointRounding.ToEven)}");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("*****Math.Round(decimal,int,MidpointRounding.ToEven)*END*********************");
            #endregion
            
            Console.ReadKey();

参考：https://docs.microsoft.com/zh-cn/dotnet/api/system.math.round?redirectedfrom=MSDN&view=netframework-4.7.2