C#中Math.Round（）实现中国式四舍五⼊
C#中Math.Round()实现中国式四舍五⼊
C#中的Math.Round()并不是使⽤的"四舍五⼊"法。其实在VB、VBScript、C#、J#、T-SQL中Round函数都是采⽤Banker's rounding（银⾏家算法），即：四舍六⼊五取偶。事实上这也是IEEE的规范，因此所有符合IEEE标准的语⾔都应该采⽤这样的算法。
.NET 2.0 开始，Math.Round ⽅法提供了⼀个枚举选项 MidpointRounding.AwayFromZero 可以⽤来实现传统意义上的"四舍五⼊"。
即： Math.Round(4.5, MidpointRounding.AwayFromZero) = 5。
Round(Decimal)
Round(Double)
Round(Decimal, Int32)
Round(Decimal, MidpointRounding)
Round(Double, Int32)
Round(Double, MidpointRounding)
Round(Decimal, Int32, MidpointRounding)
Round(Double, Int32, MidpointRounding)
如：
Math.Round(0.4) //result:0
Math.Round(0.6) //result:1sql中round函数怎么使用
Math.Round(0.5) //result:0
Math.Round(1.5) //result:2
Math.Round(2.5) //result:2
Math.Round(3.5) //result:4
Math.Round(4.5) //result:4
Math.Round(5.5) //result:6
Math.Round(6.5) //result:6
Math.Round(7.5) //result:8
Math.Round(8.5) //result:8
Math.Round(9.5) //result:10
使⽤MidpointRounding.AwayFromZero重载后对⽐：
Math.Round(0.4, MidpointRounding.AwayFromZero); // result:0
Math.Round(0.6, MidpointRounding.AwayFromZero); // result:1
Math.Round(0.5, MidpointRounding.AwayFromZero); // result:1
Math.Round(1.5, MidpointRounding.AwayFromZero); // result:2
Math.Round(2.5, MidpointRounding.AwayFromZero); // result:3
Math.Round(3.5, MidpointRounding.AwayFromZero); // result:4
Math.Round(4.5, MidpointRounding.AwayFromZero); // result:5
Math.Round(5.5, MidpointRounding.AwayFromZero); // result:6
Math.Round(6.5, MidpointRounding.AwayFromZero); // result:7
Math.Round(7.5, MidpointRounding.AwayFromZero); // result:8
Math.Round(8.5, MidpointRounding.AwayFromZero); // result:9
Math.Round(9.5, MidpointRounding.AwayFromZero); // result:10
但是悲剧的是，如果⽤这个计算⼩数的话，就不灵了！！！
必须⽤第七个重载⽅法，
decimal Round(decimal d, int decimals, MidpointRounding mode)这样计算出来的⼩数才是真正的中国式四舍五⼊！！
?Math.Round(526.925, 2)
526.92
?Math.Round(526.925, 2,MidpointRounding.AwayFromZero)
526.92
?Math.Round((decimal)526.925, 2)
526.92
?Math.Round((decimal)526.925, 2,MidpointRounding.AwayFromZero)
526.93

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