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聊一聊c#中的MATH.ROUND方法

摘要：
微软对MATH.ROUND方法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。此方法具有以下8个重载：///&lt；摘要&gt；///将十进制值舍入为最接近的整数值///&lt；/摘要&gt；///&书信电报；paramname=“d”&gt；要舍入的小数&lt；/param&gt；///&书信电报；回报&gt；最接近参数d的整数。如果d的小数部分正好位于两个整数的中间

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：

聊一聊c#中的MATH.ROUND方法第1张

 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：

　　聊一聊c#中的MATH.ROUND方法第2张

 　　1.2、decimal Round(decimal d)输出结果为：

　　聊一聊c#中的MATH.ROUND方法第3张

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

　　聊一聊c#中的MATH.ROUND方法第4张

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

　　聊一聊c#中的MATH.ROUND方法第5张

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

　　聊一聊c#中的MATH.ROUND方法第6张

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

　　聊一聊c#中的MATH.ROUND方法第7张

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

　　聊一聊c#中的MATH.ROUND方法第8张

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

　　聊一聊c#中的MATH.ROUND方法第9张

 2、得到两位小数

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

　　聊一聊c#中的MATH.ROUND方法第10张

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

　　聊一聊c#中的MATH.ROUND方法第11张

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

　　聊一聊c#中的MATH.ROUND方法第12张

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

　　聊一聊c#中的MATH.ROUND方法第13张

 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：

聊一聊c#中的MATH.ROUND方法第14张聊一聊c#中的MATH.ROUND方法第15张
#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();
View Code

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

 

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