C＃中的Decimal.Round()方法套装– 1

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：

• 舍入(十进制)方法
• Round(Decimal，Int32)方法
• 舍入(十进制，中点舍入)方法
• Round(Decimal，Int32，MidpointRounding)方法

在这里，我们将讨论前两种方法。

Decimal.Round(Decimal)方法

此方法用于将十进制值舍入到最接近的整数。

Syntax: public static decimal Round (decimal d);
Here, it takes a decimal number to round.

Return Value: This method returns the integer which is nearest to the d parameter. If d is halfway between two integers, one of which is even and the other odd, the even number is returned.

Exceptions: This method throws OverflowException if the result is outside the range of a Decimal value.

下面的程序说明了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

示例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);
        }
    }
}

编译时错误：

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

Round(Decimal，Int32)方法

此方法用于将十进制值舍入到指定的小数位数。

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

Parameters:
d: It is a decimal number which is to be rounded.
decimals: It is a value from 0 to 28 that specifies the number of decimal places to round to.

返回值：该方法返回等于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。

下面的程序说明了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

示例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/zh-cn/dotnet/api/system.decimal.round?view=netframework-4.7.2