Random.Next Method (Int32)

Returns a nonnegative random number less than the specified maximum.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

Syntax

'Declaration
Public Overridable Function Next ( _
    maxValue As Integer _
) As Integer
public virtual int Next(
    int maxValue
)

Parameters

  • maxValue
    Type: System.Int32
    The exclusive upper bound of the random number to be generated. maxValue must be greater than or equal to zero.

Return Value

Type: System.Int32
A 32-bit signed integer greater than or equal to zero, and less than maxValue; that is, the range of return values ordinarily includes zero but not maxValue. However, if maxValue equals zero, maxValue is returned.

Exceptions

Exception Condition
ArgumentOutOfRangeException

maxValue is less than zero.

Examples

The following code example generates random integers with various overloads of the Next method.

' Example of the Random.Next( ) methods.

Module Example

   ' Generate random numbers with no bounds specified.
   Sub NoBoundsRandoms(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal seed As Integer)

      outputBlock.Text &= String.Format(vbCrLf & _
          "Random object, seed = {0}, no bounds:", seed) & vbCrLf
      Dim randObj As New Random(seed)

      ' Generate six random integers from 0 to int.MaxValue.
      Dim j As Integer
      For j = 0 To 5
         outputBlock.Text &= String.Format("{0,11} ", randObj.Next())
      Next j
      outputBlock.Text &= vbCrLf
   End Sub

   ' Generate random numbers with an upper bound specified.
   Sub UpperBoundRandoms(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal seed As Integer, ByVal upper As Integer)

      outputBlock.Text &= String.Format(vbCrLf & _
          "Random object, seed = {0}, upper bound = {1}:", _
          seed, upper) & vbCrLf
      Dim randObj As New Random(seed)

      ' Generate six random integers from 0 to the upper bound.
      Dim j As Integer
      For j = 0 To 5
         outputBlock.Text &= String.Format("{0,11} ", randObj.Next(upper))
      Next j
      outputBlock.Text &= vbCrLf
   End Sub

   ' Generate random numbers with both bounds specified.
   Sub BothBoundsRandoms(ByVal outputBlock As System.Windows.Controls.TextBlock, _
       ByVal seed As Integer, ByVal lower As Integer, ByVal upper As Integer)

      outputBlock.Text &= String.Format(vbCrLf & _
          "Random object, seed = {0}, lower = {1}, " & _
          "upper = {2}:", seed, lower, upper) & vbCrLf
      Dim randObj As New Random(seed)

      ' Generate six random integers from the lower to 
      ' upper bounds.
      Dim j As Integer
      For j = 0 To 5
         outputBlock.Text &= String.Format("{0,11} ", _
             randObj.Next(lower, upper))
      Next j
      outputBlock.Text &= vbCrLf
   End Sub

   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      outputBlock.Text &= String.Format( _
          "This example of the Random.Next( ) methods" & _
          vbCrLf & "generates the following output." & vbCrLf) & vbCrLf
      outputBlock.Text &= String.Format( _
          "Create Random objects all with the same seed " & _
          "and generate" & vbCrLf & "sequences of numbers " & _
          "with different bounds. Note the effect " & vbCrLf & _
          "that the various combinations " & _
          "of bounds have on the sequences.") & vbCrLf

      NoBoundsRandoms(outputBlock, 234)

      UpperBoundRandoms(outputBlock, 234, Int32.MaxValue)
      UpperBoundRandoms(outputBlock, 234, 2000000000)
      UpperBoundRandoms(outputBlock, 234, 200000000)

      BothBoundsRandoms(outputBlock, 234, 0, Int32.MaxValue)
      BothBoundsRandoms(outputBlock, 234, Int32.MinValue, Int32.MaxValue)
      BothBoundsRandoms(outputBlock, 234, -2000000000, 2000000000)
      BothBoundsRandoms(outputBlock, 234, -200000000, 200000000)
      BothBoundsRandoms(outputBlock, 234, -2000, 2000)
   End Sub
End Module

' This example of the Random.Next( ) methods
' generates the following output.
' 
' Create Random objects all with the same seed and generate
' sequences of numbers with different bounds. Note the effect
' that the various combinations of bounds have on the sequences.
' 
' Random object, seed = 234, no bounds:
'  2091148258  1024955023   711273344  1081917183  1833298756   109460588
' 
' Random object, seed = 234, upper bound = 2147483647:
'  2091148258  1024955023   711273344  1081917183  1833298756   109460588
' 
' Random object, seed = 234, upper bound = 2000000000:
'  1947533580   954563751   662424922  1007613896  1707392518   101943116
' 
' Random object, seed = 234, upper bound = 200000000:
'   194753358    95456375    66242492   100761389   170739251    10194311
' 
' Random object, seed = 234, lower = 0, upper = 2147483647:
'  2091148258  1024955023   711273344  1081917183  1833298756   109460588
' 
' Random object, seed = 234, lower = -2147483648, upper = 2147483647:
'  2034812868   -97573602  -724936960    16350718  1519113864 -1928562472
' 
' Random object, seed = 234, lower = -2000000000, upper = 2000000000:
'  1895067160   -90872498  -675150156    15227793  1414785036 -1796113767
' 
' Random object, seed = 234, lower = -200000000, upper = 200000000:
'   189506716    -9087250   -67515016     1522779   141478503  -179611377
' 
' Random object, seed = 234, lower = -2000, upper = 2000:
'        1895         -91        -676          15        1414       -1797
// Example of the Random.Next( ) methods.
using System;

public class Example
{
   // Generate random numbers with no bounds specified.
   static void NoBoundsRandoms(System.Windows.Controls.TextBlock outputBlock, int seed)
   {
      outputBlock.Text += String.Format(
          "\nRandom object, seed = {0}, no bounds:", seed) + "\n";
      Random randObj = new Random(seed);

      // Generate six random integers from 0 to int.MaxValue.
      for (int j = 0; j < 6; j++)
         outputBlock.Text += String.Format("{0,11} ", randObj.Next());
      outputBlock.Text += "\n";
   }

   // Generate random numbers with an upper bound specified.
   static void UpperBoundRandoms(System.Windows.Controls.TextBlock outputBlock, int seed, int upper)
   {
      outputBlock.Text += String.Format(
          "\nRandom object, seed = {0}, upper bound = {1}:",
          seed, upper) + "\n";
      Random randObj = new Random(seed);

      // Generate six random integers from 0 to the upper bound.
      for (int j = 0; j < 6; j++)
         outputBlock.Text += String.Format("{0,11} ", randObj.Next(upper));
      outputBlock.Text += "\n";
   }

   // Generate random numbers with both bounds specified.
   static void BothBoundsRandoms(System.Windows.Controls.TextBlock outputBlock, int seed, int lower, int upper)
   {
      outputBlock.Text += String.Format(
          "\nRandom object, seed = {0}, lower = {1}, " +
          "upper = {2}:", seed, lower, upper) + "\n";
      Random randObj = new Random(seed);

      // Generate six random integers from the lower to 
      // upper bounds.
      for (int j = 0; j < 6; j++)
         outputBlock.Text += String.Format("{0,11} ",
             randObj.Next(lower, upper));
      outputBlock.Text += "\n";
   }

   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      outputBlock.Text += String.Format(
          "This example of the Random.Next( ) methods\n" +
          "generates the following output.\n") + "\n";
      outputBlock.Text += String.Format(
          "Create Random objects all with the same seed and " +
          "generate\nsequences of numbers with different " +
          "bounds. Note the effect\nthat the various " +
          "combinations of bounds have on the sequences.") + "\n";

      NoBoundsRandoms(outputBlock, 234);

      UpperBoundRandoms(outputBlock, 234, Int32.MaxValue);
      UpperBoundRandoms(outputBlock, 234, 2000000000);
      UpperBoundRandoms(outputBlock, 234, 200000000);

      BothBoundsRandoms(outputBlock, 234, 0, Int32.MaxValue);
      BothBoundsRandoms(outputBlock, 234, Int32.MinValue, Int32.MaxValue);
      BothBoundsRandoms(outputBlock, 234, -2000000000, 2000000000);
      BothBoundsRandoms(outputBlock, 234, -200000000, 200000000);
      BothBoundsRandoms(outputBlock, 234, -2000, 2000);
   }
}

/*
This example of the Random.Next( ) methods
generates the following output.

Create Random objects all with the same seed and generate
sequences of numbers with different bounds. Note the effect
that the various combinations of bounds have on the sequences.

Random object, seed = 234, no bounds:
 2091148258  1024955023   711273344  1081917183  1833298756   109460588

Random object, seed = 234, upper bound = 2147483647:
 2091148258  1024955023   711273344  1081917183  1833298756   109460588

Random object, seed = 234, upper bound = 2000000000:
 1947533580   954563751   662424922  1007613896  1707392518   101943116

Random object, seed = 234, upper bound = 200000000:
  194753358    95456375    66242492   100761389   170739251    10194311

Random object, seed = 234, lower = 0, upper = 2147483647:
 2091148258  1024955023   711273344  1081917183  1833298756   109460588

Random object, seed = 234, lower = -2147483648, upper = 2147483647:
 2034812868   -97573602  -724936960    16350718  1519113864 -1928562472

Random object, seed = 234, lower = -2000000000, upper = 2000000000:
 1895067160   -90872498  -675150156    15227793  1414785036 -1796113767

Random object, seed = 234, lower = -200000000, upper = 200000000:
  189506716    -9087250   -67515016     1522779   141478503  -179611377

Random object, seed = 234, lower = -2000, upper = 2000:
       1895         -91        -676          15        1414       -1797
*/

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.