C# Math.Round方法實例講解

在C#中,math.round()是Math類方法,用于將值四舍五入到最接近的整數或小數位數?？梢酝ㄟ^更改傳遞的參數的數量和類型來重載此方法。 Math.Round()方法的重載列表中共有8種方法。在這里,我們將只討論4種方法,其余4種方法將在C#中討論。 Math.Round()方法|設置-2。

• Math.Round(double)
• Math.Round(Double,Int32)
• Math.Round(decimal)
• Math.Round(Decimal,Int32)
• Math.Round(Double,Int32,MidpointRounding)
• Math.Round(Double,MidpointRounding)
• Math.Round(Decimal,Int32,MidpointRounding)
• Math.Round(decimal,MidpointRounding)

Math.Round(Double)

此方法將雙精度浮點值舍入為最接近的整數值。

用法:

public static double Round(double x)

參數:

• x:要四舍五入的雙浮點數。此參數的類型為System.Double。

返回類型:它返回最接近x的整數,返回類型為System.Double。

注意:如果x的小數部分位于兩個整數的中間,其中一個為偶數,另一個為奇數,則返回偶數。

例:

// C# program to demonstrate the? // Math.Round(Double) method using System; ??class Geeks { ??????// Main method ????static void Main(string[] args) ????{ ??????????// Case-1 ????????// A double value whose fractional part is? ????????// less than the halfway between two? ????????// consecutive integers ????????Double dx1 = 12.434565d; ??????????// Output value will be 12 ????????console.writeline("Rounded value of " + dx1 +? ??????????????????????????" is " + Math.Round(dx1)); ??????????// Case-2 ????????// A double value whose fractional part is? ????????// greater than the halfway between two? ????????// consecutive integers ????????Double dx2 = 12.634565d; ??????????// Output value will be 13 ????????Console.WriteLine("Rounded value of " + dx2 +? ??????????????????????????" is " + Math.Round(dx2)); ????} }

Rounded value of 12.434565 is 12Rounded value of 12.634565 is 13

說明:在上面的代碼中,假設用戶想要將上述指定的double值四舍五入為最接近的整數。因此,編譯器將首先檢查該double值是否大于或小于該double數的偶數和奇數整數值。如果小于中途值,則其輸出將為下限;否則,如果大于中途值,則其輸出將為上限。

Math.Round(Double, Int32)

此方法將雙精度浮點值舍入為指定數目的小數位數。

用法:

public static double Round(double x, Int32 y)

參數:

• x:要四舍五入的雙浮點數。此參數的類型為System.Double。 y:這是返回值中的小數位數。此參數的類型為System.Int32。

返回類型:它返回最接近x的整數,該整數包含與y相等的小數位數,返回類型為System.Double。

異常:如果y的值小于0或大于15,則此方法將提供ArgumentOutOfRangeException。

例:

// C# program to demonstrate the? // Math.Round(Double, Int32) method using System; ???class Geeks { ???????// Main method ????static void Main(string[] args) ????{ ???????????// double type ????????Double dx1 = 12.434565d; ???????????// using method ????????Console.WriteLine("Rounded value of " + dx1 +? ??????????????????????????" is " + Math.Round(dx1, 4)); ???????????// double type ????????Double dx2 = 12.634565d; ???????????// using method ????????Console.WriteLine("Rounded value of " + dx2 +? ??????????????????????????" is " + Math.Round(dx2,2)); ????} }

Rounded value of 12.434565 is 12.4346Rounded value of 12.634565 is 12.63

說明:方法將檢查指定的十進制數字旁邊的數字是否大于或等于5。如果它大于或等于5,則它將遞增前一個數字,否則前一個數字將保持不變。

Math.Round(Decimal)

此方法將精度為128位的十進制值四舍五入到最接近的整數值。

用法:

public static decimal Round(decimal x)

參數:

• x:是要舍入的十進制數。此參數的類型為System.Decimal。

返回類型:它返回最接近x的整數,返回類型為System.Decimal。

注意:如果x的小數部分位于兩個整數的中間,其中一個為偶數,另一個為奇數,則返回偶數。

例:

// C# program to demonstrate the? // Math.Round(Decimal) method using System; ??class Geeks { ??????// Main method ????static void Main(string[] args) ????{ ??????????// Case-1 ????????// A decimal value whose fractional part is? ????????// less than the halfway between two? ????????// consecutive integers ????????Decimal dec1 = 12.345m; ??????????Console.WriteLine("Value of dec1 is " + dec1); ??????????Console.WriteLine("Rounded value of " + dec1 +? ??????????????????????????" is " + Math.Round(dec1)); ??????????// Case-2 ????????// A double value whose fractional part is? ????????// greater than the halfway between two? ????????// consecutive integers ????????Decimal dec2 = 12.785m; ??????????Console.WriteLine("Value of dec2 is " + dec2); ??????????Console.WriteLine("Rounded value of " + dec2 +? ??????????????????????????" is " + Math.Round(dec2)); ????} }

Value of dec1 is 12.345Rounded value of 12.345 is 12Value of dec2 is 12.785Rounded value of 12.785 is 13

Math.Round(Decimal, Int32)

此方法將十進制值舍入為指定數量的小數位數。

用法:

public static decimal Round(decimal x, Int32 y)

參數:

• x:要舍入的十進制數。此參數的類型為System.Decimal。 y:這是返回值中的小數位數。此參數的類型為System.Int32。

返回類型:它返回最接近x的整數,該整數包含與y相等的小數位數,返回類型為System.Decimal。

異常:如果y的值小于0或大于15,則此方法將提供ArgumentOutOfRangeException;如果結果超出Decimal的范圍,則此方法將提供OverflowException。

例:

// C# program to demonstrate the? // Math.Round(Decimal, Int32) method using System; ??class Geeks { ??????// Main Method ????static void Main(string[] args) ????{ ??????????// Case - 1 ????????// The value of digit after specified? ????????// number is less than 5 & Here y = 3 ????????Decimal dx1 = 12.2234565m; ??????????// Output value will be 12.223 ????????Console.WriteLine("Rounded value of " + dx1 +? ??????????????????????????" is " + Math.Round(dx1, 3)); ??????????// Case - 2 ????????// The value of digit after specified? ????????// number is greater than 5 & Here y = 4 ????????Decimal dx2 = 12.8734765m; ??????????// Output value will be 12.8735 ????????Console.WriteLine("Rounded value of " + dx2 +? ??????????????????????????" is " + Math.Round(dx2, 4)); ??????} }

Rounded value of 12.2234565 is 12.223Rounded value of 12.8734765 is 12.8735

注意:上面的十進制值代碼以類似于Double值的方式工作。小數類型和雙精度類型之間的唯一區別在于精度的概念,即在Double的情況下,精度為64位,在Decimal精度的情況下為128位。

參考: https://docs.microsoft.com/en-us/dotnet/api/system.math.round?view=netframework-4.7.2