vb System.Double.Epsilon类(方法)实例源码

Module Example
   Public Sub Main()
      Dim values() As Double = { 0, Double.Epsilon, Double.Epsilon * .5 }
      
      For ctr As Integer = 0 To values.Length - 2
         For ctr2 As Integer = ctr + 1 To values.Length - 1
            Console.WriteLine("{0:r} = {1:r}: {2}", _
                              values(ctr), values(ctr2), _ 
                              values(ctr).Equals(values(ctr2)))
         Next
         Console.WriteLine()
      Next      
   End Sub
End Module

Module Example
   Public Sub Main()
      Dim values() As Double = { 0.0, Double.Epsilon }
      For Each value In values
         Console.WriteLine(GetComponentParts(value))
         Console.WriteLine()
      Next   
   End Sub

   Private Function GetComponentParts(value As Double) As String
      Dim result As String =  String.Format("{0:R}: ", value)
      Dim indent As Integer =  result.Length

      ' Convert the double to an 8-byte array.
      Dim bytes() As Byte = BitConverter.GetBytes(value)
      ' Get the sign bit (byte 7, bit 7).
      result += String.Format("Sign: {0}{1}", 
                              If((bytes(7) And &H80) = &H80, "1 (-)", "0 (+)"),
                              vbCrLf)

      ' Get the exponent (byte 6 bits 4-7 to byte 7, bits 0-6)
      Dim exponent As Integer =  (bytes(7) And &H07F) << 4
      exponent = exponent Or ((bytes(6) And &HF0) >> 4)  
      Dim adjustment As Integer = If(exponent <> 0, 1023, 1022)
      result += String.Format("{0}Exponent: 0x{1:X4} ({1}){2}", 
                              New String(" "c, indent), exponent - adjustment,
                              vbCrLf)

      ' Get the significand (bits 0-51)
      Dim significand As Long =  ((bytes(6) And &H0F) << 48) 
      significand = significand Or (bytes(5) << 40)
      significand = significand Or (bytes(4) << 32)
      significand = significand Or (bytes(3) << 24)
      significand = significand Or (bytes(2) << 16)
      significand = significand Or (bytes(1) << 8)
      significand = significand Or bytes(0)    
      result += String.Format("{0}Mantissa: 0x{1:X13}{2}", 
                              New String(" "c, indent), significand, vbCrLf)    

      Return result   
   End Function
End Module

public class Test
   public Shared Sub Main
        Dim D As Double
    
        D = 5
        Console.WriteLine(D.Epsilon)

   End Sub
End class