Random.NextBytes Method

Each element of the array of bytes is set to a random number greater than or equal to zero, and less than or equal to MaxValue.

To generate a cryptographically secured random number suitable for creating a random password, for example, use a method such as RNGCryptoServiceProvider.GetBytes.

Starting with the .NET Framework version 2.0, if you derive a class from Random and override the Sample method, the distribution provided by the derived class implementation of the Sample method is not used in calls to the base class implementation of the NextBytes method. Instead, the uniform distribution returned by the base Random class is used. This behavior improves the overall performance of the Random class. To modify this behavior to call the Sample method in the derived class, you must also override the NextBytes method.

The following example demonstrates how to use the NextBytes method to fill an array of bytes with random byte values.

Public Class Example
    Public Shared Sub Main()
        Dim rnd As New Random()
        Dim b(9) As Byte
        rnd.NextBytes(b)
        Console.WriteLine("The Random bytes are: ")
        For i As Integer = 0 To b.GetUpperBound(0)
            Console.WriteLine("{0}: {1}", i, b(i))
        Next 
    End Sub  
End Class  
' The example displays output similar to the following: 
'       The Random bytes are: 
'       0: 131 
'       1: 96 
'       2: 226 
'       3: 213 
'       4: 176 
'       5: 208 
'       6: 99 
'       7: 89 
'       8: 226 
'       9: 194

.NET Framework

.NET Framework Client Profile

Portable Class Library

.NET for Windows Store apps

Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference