C＃中的MathF.Round()方法，包含示例|套装– 2

在C＃中， MathF.Round()是MathF类方法，用于将值四舍五入到最接近的整数或小数位数。它返回数字的最接近的值，其精度等于传递的第二个参数。如果要舍入的值恰好介于偶数和奇数之间，则返回偶数。 MathF.Round适用IEEE标准754，第4节。可以通过更改传递的参数的数量和类型来重载此方法。 MathF.Round()方法的重载列表中有4种方法，如下所示：

1. MathF.Round(Single)方法
2. MathF.Round(Single，Int32)方法
3. MathF.Round(Single，Int32，MidpointRounding)方法
4. MathF.Round(Single，MidpointRounding)方法

在这里，我们将讨论最后两种方法。

Math.Round(Single，Int32，MidpointRounding)方法

此方法用于将单个精度浮点值四舍五入为指定数量的小数位数。参数指定如果值在两个数字之间的中间值时如何舍入。

Syntax: public static float Round (float x, int digits, MidpointRounding mode);

Parameters:

x: It is the required single-precision floating-point number which is to be rounded and type of this parameter is System.Single.

digits: It is the number of fractional digits in the return value and type of this parameter is System.Int32.

mode: Specification for how to round x if it is midway between two other numbers and works as MidpointRounding.

返回类型：此方法返回最接近x的数字，该数字的小数位数等于digits 。如果x的小数位数少于digits ，则x不变返回。此方法的返回类型为System.Single 。

例外情况：

• ArgumentOutOfRangeException ：如果数字小于0或大于15。
• ArgumentException ：如果该模式不是MidpointRounding的有效值。

例子：

// C# program to demonstrate the
// MathF.Round(Single, Int32,
// MidpointRounding) method
using System;
  
class Geeks {
  
    // Main Method
    public static void Main()
    {
        // The 4 values are store in an float
        // type array name 'val'
        float[] x = { 8.115f, 7.135f, 9.165f, 6.175f };
  
        Console.WriteLine("Rounded values are:");
  
        // 'foreach' loop iterates through
        // each item from the array 'values'
        // and storing the items in a new
        // variable 'x'
        foreach(float value in x)
  
            // '{0}' specify the variable 'x' which is
            // in 'foreach' loop and '{1}' specify the
            // rounded value, here '2' defines the number
            // of digit after point, e.g. 4.135f == 4.14f,
            // after '4f.' there is 2 digits'.14f'
            // and here '.ToEven' select the nearest even
            // number e.g 4.125f == 4.12f, here nearest even
            // number is '12f',
            Console.WriteLine("{0} == {1}", value, MathF.Round(value, 2,
                                              MidpointRounding.ToEven));
    }
}

输出：

Rounded values are:
8.115 == 8.12
7.135 == 7.14
9.165 == 9.16
6.175 == 6.18

MathF.Round(Single，MidpointRounding)方法

此方法用于将单个精度浮点值舍入到最接近的整数。参数指定如果值在两个数字之间的中间值时如何舍入。

Syntax: public static float Round (float x, MidpointRounding mode);

Parameters:

x: It is the required single-precision floating-point number which is to be rounded and type of this parameter is System.Single.

mode: Specification for how to round x if it is midway between two other numbers and works as MidpointRounding.

返回类型：此方法返回整数最接近的值。如果x位于两个整数之间的中间，其中一个为偶数，另一个为奇数，则mode确定返回两个中的哪一个。此方法的返回类型为System.Single 。

异常：如果该模式不是MidpointRounding的有效值，则此方法提供ArgumentException。

例子：

// C# program to demonstrate the
// MathF.Round(Single, MidpointRounding) 
// method
using System;
  
class Geeks {
  
    // Main Method
    public static void Main()
    {
  
        // 'x' is float type variable
        // which holds the value 7.1f
        float x = 7.1f;
  
        Console.WriteLine("Inside Loop:\n");
  
        //'for loop', it execute the next
        // output for 8 times
        for (int i = 0; i <= 8; i++) {
  
            // '{0}' specify the variable 'x' and
            // '{1}' specify the rounded value
            Console.WriteLine("{0} = {1}", x, MathF.Round(x,
                            MidpointRounding.AwayFromZero));
  
            // increment 'x' by '0.1'
            x += 0.1f;
        }
  
        // a new value is assigned
        // to variable 'x'
        x = 4.5f;
  
        // prints a new line
        Console.WriteLine();
  
        //'{0}'specify the variable 'x' in which a new
        // value 4.5f is assigned and '{1}' specify the
        // new rounded value
        Console.WriteLine("Outside Loop : {0} = {1}", x,
          MathF.Round(x, MidpointRounding.AwayFromZero));
    }
}

输出：

Inside Loop:

7.1 = 7
7.2 = 7
7.3 = 7
7.4 = 7
7.5 = 7
7.599999 = 8
7.699999 = 8
7.799999 = 8
7.899999 = 8

Outside Loop : 4.5 = 5