C# Decimal.Round()方法实例讲解

Decimal.Round方法用于将值舍入到最接近的整数或指定数量的小数位数。此方法的重载列表中有4种方法，如下所示：

Round(Decimal) 方法
Round(Decimal，Int32)方法
Round(Decimal, MidpointRounding) 方法
Round(Decimal，Int32，MidpointRounding)方法

在这里，我们将讨论前两种方法。

Decimal.Round(Decimal) Method

此方法用于将十进制值舍入到最接近的整数。

用法： public static decimal Round (decimal d);

Here, it takes a decimal number to round.

返回值：此方法返回最接近d参数的整数。如果d在两个整数之间，其中一个是偶数，另一个是奇数，则返回偶数。

异常：如果结果超出Decimal值的范围，则此方法将引发OverflowException。

以下示例程序旨在说明Decimal.Round(Decimal)方法的用法：

范例1：

// C# program to demonstrate the 
// Decimal.Round(Decimal) Method 
using System; 
  
class GFG { 
  
    // Main Method 
    public static void Main() 
    { 
        try { 
  
            // Declaring and initializing value 
            decimal value = 184467440737095.51615M; 
  
            // getting rounded decimal 
            // using Round() method 
            decimal round = Decimal.Round(value); 
  
            // Display the value 
            Console.WriteLine("Rounded value is {0}", round); 
        } 
  
        catch (OverflowException e)  
        { 
            Console.WriteLine("Value must not be out of bound"); 
            Console.Write("Exception Thrown:"); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
    } 
}

输出：

Rounded value is 184467440737096

范例2：对于OverflowException

// C# program to demonstrate the 
// Decimal.Round(Decimal) Method 
using System; 
  
class GFG { 
  
    // Main Method 
    public static void Main() 
    { 
  
        try 
        { 
  
            // Declaring and initializing value 
            decimal value = 79228162514264337593543950335.5M; 
  
            // getting rounded decimal 
            // using Round() method 
            decimal round = Decimal.Round(value); 
  
            // Display the value 
            Console.WriteLine("Rounded value is {0}", round); 
        } 
  
        catch (OverflowException e)  
        { 
            Console.WriteLine("Value must not be out of bound"); 
            Console.Write("Exception Thrown:"); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
    } 
}

Compile-Time错误：

prog.cs(15,51):error CS0594:Floating-point constant is outside the range of type `decimal’

Round(Decimal, Int32) Method

此方法用于将十进制值舍入到指定的小数位数。

用法： public static decimal Round (decimal d, int decimals);

参数：
d:它是一个十进制数，将被四舍五入。
decimals:从0到28的值，指定要舍入到的小数位数。

返回值：此方法返回等于d的十进制数，四舍五入为小数位的小数位数。

异常：如果小数位数不是0到28之间的值，则此方法将引发ArgumentOutOfRangeException。

以下示例程序旨在说明Decimal.Round(Decimal，Int32)方法的用法：

范例1：

// C# program to demonstrate the 
// Decimal.Round(Decimal) Method 
using System; 
  
class GFG { 
  
    // Main Method 
    public static void Main() 
    { 
        try { 
  
            // Declaring and initializing value 
            decimal value = 7922816251426433759354.39503305M; 
  
            // getting rounded decimal 
            // using Round() method 
            decimal round = Decimal.Round(value, 4); 
  
            // Display the value 
            Console.WriteLine("Rounded value is {0}", round); 
        } 
  
        catch (ArgumentOutOfRangeException e)  
        { 
            Console.WriteLine("decimal place is not within bound"); 
            Console.Write("Exception Thrown:"); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
    } 
}

输出：

Rounded value is 7922816251426433759354.3950

范例2：对于ArgumentOutOfRangeException

// C# program to demonstrate the 
// Decimal.Round(Decimal) Method 
using System; 
  
class GFG { 
  
    // Main Method 
    public static void Main() 
    { 
        try 
        { 
  
            // Declaring and initializing value 
            decimal value = 7922816251426433759354.39503305M; 
  
            // getting rounded decimal 
            // using Round() method 
            decimal round = Decimal.Round(value, 29); 
  
            // Display the value 
            Console.WriteLine("Rounded value is {0}", round); 
        } 
  
        catch (ArgumentOutOfRangeException e)  
        { 
            Console.WriteLine("Decimal place is not within bound"); 
            Console.Write("Exception Thrown:"); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
    } 
}

输出：

Decimal place is not within bound
Exception Thrown:System.ArgumentOutOfRangeException

参考：

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