vb System.Random.NextDouble类(方法)实例源码

' Example of the Random class constructors and Random.NextDouble( ) 
' method.
Imports System.Threading

Module RandomObjectDemo

    ' Generate random numbers from the specified Random object.
    Sub RunIntNDoubleRandoms( randObj As Random )

        ' Generate the first six random integers.
        Dim j As Integer
        For j = 0 To 5
            Console.Write( " {0,10} ", randObj.Next( ) )
        Next j
        Console.WriteLine( )
            
        ' Generate the first six random doubles.
        For j = 0 To 5
            Console.Write( " {0:F8} ", randObj.NextDouble( ) )
        Next j
        Console.WriteLine( )
    End Sub 
        
    ' Create a Random object with the specified seed.
    Sub FixedSeedRandoms( seed As Integer )

        Console.WriteLine( vbCrLf & _
            "Random numbers from a Random object with " & _
            "seed = {0}:", seed )
        Dim fixRand As New Random( seed )
            
        RunIntNDoubleRandoms( fixRand )
    End Sub 
        
    ' Create a random object with a timer-generated seed.
    Sub AutoSeedRandoms( )

        ' Wait to allow the timer to advance.
        Thread.Sleep( 1 )
            
        Console.WriteLine( vbCrLf & _
            "Random numbers from a Random object " & _ 
            "with an auto-generated seed:" )
        Dim autoRand As New Random( )
            
        RunIntNDoubleRandoms( autoRand )
    End Sub 
        
    Sub Main( )
        Console.WriteLine( _
            "This example of the Random class constructors " & _
            "and Random.NextDouble( ) " & vbCrLf & _
            "generates the following output." & vbCrLf )
        Console.WriteLine( "Create Random " & _
            "objects, and then generate and display six " & _
            "integers and " & vbCrLf & "six doubles from each." )
            
        FixedSeedRandoms( 123 )
        FixedSeedRandoms( 123 )
            
        FixedSeedRandoms( 456 )
        FixedSeedRandoms( 456 )
            
        AutoSeedRandoms( )
        AutoSeedRandoms( )
        AutoSeedRandoms( )
    End Sub
End Module 

' This example of the Random class constructors and Random.NextDouble( )

Module Example
   Public Sub Main()
      Dim frequency(9) As Integer
      Dim number As Double
      Dim rnd As New Random()
      
      For ctr As Integer = 0 To 99
         number = rnd.NextDouble()
         frequency(CInt(Math.Floor(number*10))) += 1
      Next
      Console.WriteLine("Distribution of Random Numbers:")
      For ctr As Integer = frequency.GetLowerBound(0) To frequency.GetUpperBound(0)
         Console.WriteLine("0.{0}0-0.{0}9       {1}", ctr, frequency(ctr))
      Next         
   End Sub
End Module
' The following example displays output similar to the following:
'       Distribution of Random Numbers:
'       0.00-0.09       16
'       0.10-0.19       8
'       0.20-0.29       8
'       0.30-0.39       11
'       0.40-0.49       9
'       0.50-0.59       6
'       0.60-0.69       13
'       0.70-0.79       6
'       0.80-0.89       9
'       0.90-0.99       14