Random.NextBytes Method

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Overloads

NextBytes(Span<Byte>)	Fills the elements of a specified span of bytes with random numbers.
NextBytes(Byte[])	Fills the elements of a specified array of bytes with random numbers.

NextBytes(Span<Byte>)

Source:

Random.cs

Fills the elements of a specified span of bytes with random numbers.

public:
 virtual void NextBytes(Span<System::Byte> buffer);

public virtual void NextBytes (Span<byte> buffer);

abstract member NextBytes : Span<byte> -> unit
override this.NextBytes : Span<byte> -> unit

Public Overridable Sub NextBytes (buffer As Span(Of Byte))

Parameters

buffer

Span<Byte>

The array to be filled with random numbers.

Remarks

Each element of the span of bytes is set to a random number greater than or equal to 0 and less than or equal to MaxValue.

NextBytes(Byte[])

Source:

Random.cs

Fills the elements of a specified array of bytes with random numbers.

public:
 virtual void NextBytes(cli::array <System::Byte> ^ buffer);

public virtual void NextBytes (byte[] buffer);

abstract member NextBytes : byte[] -> unit
override this.NextBytes : byte[] -> unit

Public Overridable Sub NextBytes (buffer As Byte())

Parameters

buffer

Byte[]

The array to be filled with random numbers.

Exceptions

ArgumentNullException

buffer is null.

Examples

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

#using <System.DLL>

using namespace System;

void main()
{
   Random^ rnd = gcnew Random;
   array<unsigned char>^b = gcnew array<unsigned char>(10);
   rnd->NextBytes( b );
   Console::WriteLine("The Random bytes are:");
   for ( int i = 0; i < 10; i++ )
      Console::WriteLine("{0}: {1}", i, b[i]);
}
// 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

Random rnd = new Random();
Byte[] b = new Byte[10];
rnd.NextBytes(b);
Console.WriteLine("The Random bytes are: ");
for (int i = 0; i <= b.GetUpperBound(0); i++)
    Console.WriteLine("{0}: {1}", i, b[i]);

// 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

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

Remarks

Each element of the array of bytes is set to a random number greater than or equal to 0, and less than or equal to MaxValue.

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

Notes to Inheritors

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(Byte[]) 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(Byte[]) method.

See also

• Byte