Random.Next Method
Definition
Important
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Returns a random integer.
Overloads
Next() |
Returns a non-negative random integer. |
Next(Int32) |
Returns a non-negative random integer that is less than the specified maximum. |
Next(Int32, Int32) |
Returns a random integer that is within a specified range. |
Next()
- Source:
- Random.cs
- Source:
- Random.cs
- Source:
- Random.cs
Returns a non-negative random integer.
public:
virtual int Next();
public virtual int Next ();
abstract member Next : unit -> int
override this.Next : unit -> int
Public Overridable Function Next () As Integer
Returns
A 32-bit signed integer that is greater than or equal to 0 and less than Int32.MaxValue.
Examples
The following example makes repeated calls to the Next method to generate 10 random numbers.
using namespace System;
void main()
{
Console::Write("Number of random numbers to generate: ");
String^ line = Console::ReadLine();
unsigned int numbers = 0;
Random^ rnd = gcnew Random();
if (!UInt32::TryParse(line, numbers))
numbers = 10;
for (unsigned int ctr = 1; ctr <= numbers; ctr++)
Console::WriteLine("{0,15:N0}", rnd->Next());
}
// The example displays output like the following when asked to generate
// 15 random numbers:
// Number of random numbers to generate: 15
// 1,733,189,596
// 566,518,090
// 1,166,108,546
// 1,931,426,514
// 1,341,108,291
// 1,012,698,049
// 890,578,409
// 1,377,589,722
// 2,108,384,181
// 1,532,939,448
// 762,207,767
// 815,074,920
// 1,521,208,785
// 1,950,436,671
// 1,266,596,666
Console.WriteLine("Generating 10 random numbers:");
Random rnd = new();
for (uint ctr = 1; ctr <= 10; ctr++)
Console.WriteLine($"{rnd.Next(),15:N0}");
// The example displays output like the following:
//
// Generating 10 random numbers:
// 1,733,189,596
// 566,518,090
// 1,166,108,546
// 1,931,426,514
// 1,532,939,448
// 762,207,767
// 815,074,920
// 1,521,208,785
// 1,950,436,671
// 1,266,596,666
let rnd = Random()
printfn "Generating 10 random numbers:"
for _ = 1 to 10 do
printfn $"{rnd.Next(),15:N0}"
// The example displays output like the following:
//
// Generating 10 random numbers:
// 1,733,189,596
// 566,518,090
// 1,166,108,546
// 1,931,426,514
// 1,532,939,448
// 762,207,767
// 815,074,920
// 1,521,208,785
// 1,950,436,671
// 1,266,596,666
Module Example
Public Sub Main()
Console.Write("Number of random numbers to generate: ")
Dim line As String = Console.ReadLine()
Dim numbers As UInteger = 0
Dim rnd As New Random()
If Not UInt32.TryParse(line, numbers) Then numbers = 10
For ctr As UInteger = 1 To numbers
Console.WriteLine("{0,15:N0}", rnd.Next())
Next
End Sub
End Module
' The example displays output like the following when asked to generate
' 15 random numbers:
' Number of random numbers to generate: 15
' 1,733,189,596
' 566,518,090
' 1,166,108,546
' 1,931,426,514
' 1,341,108,291
' 1,012,698,049
' 890,578,409
' 1,377,589,722
' 2,108,384,181
' 1,532,939,448
' 762,207,767
' 815,074,920
' 1,521,208,785
' 1,950,436,671
' 1,266,596,666
The following example derives a class from Random to generate a sequence of random numbers whose distribution differs from the uniform distribution generated by the Sample method of the base class. It overrides the Sample method to provide the distribution of random numbers, and overrides the Random.Next method to use series of random numbers.
using namespace System;
// This derived class converts the uniformly distributed random
// numbers generated by base.Sample() to another distribution.
public ref class RandomProportional : Random
{
// The Sample method generates a distribution proportional to the value
// of the random numbers, in the range [0.0, 1.0].
protected:
virtual double Sample() override
{
return Math::Sqrt(Random::Sample());
}
public:
RandomProportional()
{}
virtual int Next() override
{
return (int) (Sample() * Int32::MaxValue);
}
};
int main(array<System::String ^> ^args)
{
const int rows = 4, cols = 6;
const int runCount = 1000000;
const int distGroupCount = 10;
const double intGroupSize =
((double) Int32::MaxValue + 1.0) / (double)distGroupCount;
RandomProportional ^randObj = gcnew RandomProportional();
array<int>^ intCounts = gcnew array<int>(distGroupCount);
array<int>^ realCounts = gcnew array<int>(distGroupCount);
Console::WriteLine(
"\nThe derived RandomProportional class overrides " +
"the Sample method to \ngenerate random numbers " +
"in the range [0.0, 1.0]. The distribution \nof " +
"the numbers is proportional to their numeric values. " +
"For example, \nnumbers are generated in the " +
"vicinity of 0.75 with three times the \n" +
"probability of those generated near 0.25.");
Console::WriteLine(
"\nRandom doubles generated with the NextDouble() " +
"method:\n");
// Generate and display [rows * cols] random doubles.
for (int i = 0; i < rows; i++)
{
for (int j = 0; j < cols; j++)
Console::Write("{0,12:F8}", randObj->NextDouble());
Console::WriteLine();
}
Console::WriteLine(
"\nRandom integers generated with the Next() " +
"method:\n");
// Generate and display [rows * cols] random integers.
for (int i = 0; i < rows; i++)
{
for (int j = 0; j < cols; j++)
Console::Write("{0,12}", randObj->Next());
Console::WriteLine();
}
Console::WriteLine(
"\nTo demonstrate the proportional distribution, " +
"{0:N0} random \nintegers and doubles are grouped " +
"into {1} equal value ranges. This \n" +
"is the count of values in each range:\n",
runCount, distGroupCount);
Console::WriteLine(
"{0,21}{1,10}{2,20}{3,10}", "Integer Range",
"Count", "Double Range", "Count");
Console::WriteLine(
"{0,21}{1,10}{2,20}{3,10}", "-------------",
"-----", "------------", "-----");
// Generate random integers and doubles, and then count
// them by group.
for (int i = 0; i < runCount; i++)
{
intCounts[ (int)((double)randObj->Next() /
intGroupSize) ]++;
realCounts[ (int)(randObj->NextDouble() *
(double)distGroupCount) ]++;
}
// Display the count of each group.
for (int i = 0; i < distGroupCount; i++)
Console::WriteLine(
"{0,10}-{1,10}{2,10:N0}{3,12:N5}-{4,7:N5}{5,10:N0}",
(int)((double)i * intGroupSize),
(int)((double)(i + 1) * intGroupSize - 1.0),
intCounts[ i ],
((double)i) / (double)distGroupCount,
((double)(i + 1)) / (double)distGroupCount,
realCounts[ i ]);
return 0;
}
/*
This example of Random.Sample() displays output similar to the following:
The derived RandomProportional class overrides the Sample method to
generate random numbers in the range [0.0, 1.0). The distribution
of the numbers is proportional to the number values. For example,
numbers are generated in the vicinity of 0.75 with three times the
probability of those generated near 0.25.
Random doubles generated with the NextDouble() method:
0.59455719 0.17589882 0.83134398 0.35795862 0.91467727 0.54022658
0.93716947 0.54817519 0.94685080 0.93705478 0.18582318 0.71272428
0.77708682 0.95386216 0.70412393 0.86099417 0.08275804 0.79108316
0.71019941 0.84205103 0.41685082 0.58186880 0.89492302 0.73067715
Random integers generated with the Next() method:
1570755704 1279192549 1747627711 1705700211 1372759203 1849655615
2046235980 1210843924 1554274149 1307936697 1480207570 1057595022
337854215 844109928 2028310798 1386669369 2073517658 1291729809
1537248240 1454198019 1934863511 1640004334 2032620207 534654791
To demonstrate the proportional distribution, 1,000,000 random
integers and doubles are grouped into 10 equal value ranges. This
is the count of values in each range:
Integer Range Count Double Range Count
------------- ----- ------------ -----
0- 214748363 10,079 0.00000-0.10000 10,148
214748364- 429496728 29,835 0.10000-0.20000 29,849
429496729- 644245093 49,753 0.20000-0.30000 49,948
644245094- 858993458 70,325 0.30000-0.40000 69,656
858993459-1073741823 89,906 0.40000-0.50000 90,337
1073741824-1288490187 109,868 0.50000-0.60000 110,225
1288490188-1503238552 130,388 0.60000-0.70000 129,986
1503238553-1717986917 149,231 0.70000-0.80000 150,428
1717986918-1932735282 170,234 0.80000-0.90000 169,610
1932735283-2147483647 190,381 0.90000-1.00000 189,813
*/
using System;
// This derived class converts the uniformly distributed random
// numbers generated by base.Sample() to another distribution.
public class RandomProportional : Random
{
// The Sample method generates a distribution proportional to the value
// of the random numbers, in the range [0.0, 1.0].
protected override double Sample()
{
return Math.Sqrt(base.Sample());
}
public override int Next()
{
return (int) (Sample() * int.MaxValue);
}
}
public class RandomSampleDemo
{
static void Main()
{
const int rows = 4, cols = 6;
const int runCount = 1000000;
const int distGroupCount = 10;
const double intGroupSize =
((double)int.MaxValue + 1.0) / (double)distGroupCount;
RandomProportional randObj = new RandomProportional();
int[ ] intCounts = new int[ distGroupCount ];
int[ ] realCounts = new int[ distGroupCount ];
Console.WriteLine(
"\nThe derived RandomProportional class overrides " +
"the Sample method to \ngenerate random numbers " +
"in the range [0.0, 1.0]. The distribution \nof " +
"the numbers is proportional to their numeric values. " +
"For example, \nnumbers are generated in the " +
"vicinity of 0.75 with three times the \n" +
"probability of those generated near 0.25.");
Console.WriteLine(
"\nRandom doubles generated with the NextDouble() " +
"method:\n");
// Generate and display [rows * cols] random doubles.
for (int i = 0; i < rows; i++)
{
for (int j = 0; j < cols; j++)
Console.Write("{0,12:F8}", randObj.NextDouble());
Console.WriteLine();
}
Console.WriteLine(
"\nRandom integers generated with the Next() " +
"method:\n");
// Generate and display [rows * cols] random integers.
for (int i = 0; i < rows; i++)
{
for (int j = 0; j < cols; j++)
Console.Write("{0,12}", randObj.Next());
Console.WriteLine();
}
Console.WriteLine(
"\nTo demonstrate the proportional distribution, " +
"{0:N0} random \nintegers and doubles are grouped " +
"into {1} equal value ranges. This \n" +
"is the count of values in each range:\n",
runCount, distGroupCount);
Console.WriteLine(
"{0,21}{1,10}{2,20}{3,10}", "Integer Range",
"Count", "Double Range", "Count");
Console.WriteLine(
"{0,21}{1,10}{2,20}{3,10}", "-------------",
"-----", "------------", "-----");
// Generate random integers and doubles, and then count
// them by group.
for (int i = 0; i < runCount; i++)
{
intCounts[ (int)((double)randObj.Next() /
intGroupSize) ]++;
realCounts[ (int)(randObj.NextDouble() *
(double)distGroupCount) ]++;
}
// Display the count of each group.
for (int i = 0; i < distGroupCount; i++)
Console.WriteLine(
"{0,10}-{1,10}{2,10:N0}{3,12:N5}-{4,7:N5}{5,10:N0}",
(int)((double)i * intGroupSize),
(int)((double)(i + 1) * intGroupSize - 1.0),
intCounts[ i ],
((double)i) / (double)distGroupCount,
((double)(i + 1)) / (double)distGroupCount,
realCounts[ i ]);
}
}
/*
This example of Random.Sample() displays output similar to the following:
The derived RandomProportional class overrides the Sample method to
generate random numbers in the range [0.0, 1.0). The distribution
of the numbers is proportional to the number values. For example,
numbers are generated in the vicinity of 0.75 with three times the
probability of those generated near 0.25.
Random doubles generated with the NextDouble() method:
0.59455719 0.17589882 0.83134398 0.35795862 0.91467727 0.54022658
0.93716947 0.54817519 0.94685080 0.93705478 0.18582318 0.71272428
0.77708682 0.95386216 0.70412393 0.86099417 0.08275804 0.79108316
0.71019941 0.84205103 0.41685082 0.58186880 0.89492302 0.73067715
Random integers generated with the Next() method:
1570755704 1279192549 1747627711 1705700211 1372759203 1849655615
2046235980 1210843924 1554274149 1307936697 1480207570 1057595022
337854215 844109928 2028310798 1386669369 2073517658 1291729809
1537248240 1454198019 1934863511 1640004334 2032620207 534654791
To demonstrate the proportional distribution, 1,000,000 random
integers and doubles are grouped into 10 equal value ranges. This
is the count of values in each range:
Integer Range Count Double Range Count
------------- ----- ------------ -----
0- 214748363 10,079 0.00000-0.10000 10,148
214748364- 429496728 29,835 0.10000-0.20000 29,849
429496729- 644245093 49,753 0.20000-0.30000 49,948
644245094- 858993458 70,325 0.30000-0.40000 69,656
858993459-1073741823 89,906 0.40000-0.50000 90,337
1073741824-1288490187 109,868 0.50000-0.60000 110,225
1288490188-1503238552 130,388 0.60000-0.70000 129,986
1503238553-1717986917 149,231 0.70000-0.80000 150,428
1717986918-1932735282 170,234 0.80000-0.90000 169,610
1932735283-2147483647 190,381 0.90000-1.00000 189,813
*/
' This derived class converts the uniformly distributed random
' numbers generated by base.Sample() to another distribution.
Public Class RandomProportional
Inherits Random
' The Sample method generates a distribution proportional to the value
' of the random numbers, in the range [0.0, 1.0].
Protected Overrides Function Sample() As Double
Return Math.Sqrt(MyBase.Sample())
End Function
Public Overrides Function [Next]() As Integer
Return Sample() * Integer.MaxValue
End Function
End Class
Module RandomSampleDemo
Sub Main()
Const rows As Integer = 4, cols As Integer = 6
Const runCount As Integer = 1000000
Const distGroupCount As Integer = 10
Const intGroupSize As Double = _
(CDbl(Integer.MaxValue) + 1.0) / _
CDbl(distGroupCount)
Dim randObj As New RandomProportional()
Dim intCounts(distGroupCount) As Integer
Dim realCounts(distGroupCount) As Integer
Dim i As Integer, j As Integer
Console.WriteLine(vbCrLf & _
"The derived RandomProportional class overrides " & _
"the Sample method to " & vbCrLf & _
"generate random numbers in the range " & _
"[0.0, 1.0]. The distribution " & vbCrLf & _
"of the numbers is proportional to their numeric " & _
"values. For example, " & vbCrLf & _
"numbers are generated in the vicinity of 0.75 " & _
"with three times " & vbCrLf & "the " & _
"probability of those generated near 0.25.")
Console.WriteLine(vbCrLf & _
"Random doubles generated with the NextDouble() " & _
"method:" & vbCrLf)
' Generate and display [rows * cols] random doubles.
For i = 0 To rows - 1
For j = 0 To cols - 1
Console.Write("{0,12:F8}", randObj.NextDouble())
Next j
Console.WriteLine()
Next i
Console.WriteLine(vbCrLf & _
"Random integers generated with the Next() " & _
"method:" & vbCrLf)
' Generate and display [rows * cols] random integers.
For i = 0 To rows - 1
For j = 0 To cols - 1
Console.Write("{0,12}", randObj.Next())
Next j
Console.WriteLine()
Next i
Console.WriteLine(vbCrLf & _
"To demonstrate the proportional distribution, " & _
"{0:N0} random " & vbCrLf & _
"integers and doubles are grouped into {1} " & _
"equal value ranges. This " & vbCrLf & _
"is the count of values in each range:" & vbCrLf, _
runCount, distGroupCount)
Console.WriteLine("{0,21}{1,10}{2,20}{3,10}", _
"Integer Range", "Count", "Double Range", "Count")
Console.WriteLine("{0,21}{1,10}{2,20}{3,10}", _
"-------------", "-----", "------------", "-----")
' Generate random integers and doubles, and then count
' them by group.
For i = 0 To runCount - 1
intCounts(Fix(CDbl(randObj.Next()) / _
intGroupSize)) += 1
realCounts(Fix(randObj.NextDouble() * _
CDbl(distGroupCount))) += 1
Next i
' Display the count of each group.
For i = 0 To distGroupCount - 1
Console.WriteLine( _
"{0,10}-{1,10}{2,10:N0}{3,12:N5}-{4,7:N5}{5,10:N0}", _
Fix(CDbl(i) * intGroupSize), _
Fix(CDbl(i + 1) * intGroupSize - 1.0), _
intCounts(i), _
CDbl(i) / CDbl(distGroupCount), _
CDbl(i + 1) / CDbl(distGroupCount), _
realCounts(i))
Next i
End Sub
End Module
' This example of Random.Sample() generates output similar to the following:
'
' The derived RandomProportional class overrides the Sample method to
' generate random numbers in the range [0.0, 1.0]. The distribution
' of the numbers is proportional to their numeric values. For example,
' numbers are generated in the vicinity of 0.75 with three times
' the probability of those generated near 0.25.
'
' Random doubles generated with the NextDouble() method:
'
' 0.28377004 0.75920598 0.33430371 0.66720626 0.97080243 0.27353772
' 0.17787962 0.54618410 0.08145080 0.56286100 0.99002910 0.64898614
' 0.27673277 0.99455281 0.93778966 0.76162002 0.70533771 0.44375798
' 0.55939883 0.87383136 0.66465779 0.77392566 0.42393411 0.82409159
'
' Random integers generated with the Next() method:
'
' 1364479914 1230312341 1657373812 1526222928 988564704 700078020
' 1801013705 1541517421 1146312560 338318389 1558995993 2027260859
' 884520932 1320070465 570200106 1027684711 943035246 2088689333
' 630809089 1705728475 2140787648 2097858166 1863010875 1386804198
'
' To demonstrate the proportional distribution, 1,000,000 random
' integers and doubles are grouped into 10 equal value ranges. This
' is the count of values in each range:
'
' Integer Range Count Double Range Count
' ------------- ----- ------------ -----
' 0- 214748363 9,892 0.00000-0.10000 9,928
' 214748364- 429496728 30,341 0.10000-0.20000 30,101
' 429496729- 644245093 49,958 0.20000-0.30000 49,964
' 644245094- 858993458 70,099 0.30000-0.40000 70,213
' 858993459-1073741823 90,801 0.40000-0.50000 89,553
' 1073741824-1288490187 109,699 0.50000-0.60000 109,427
' 1288490188-1503238552 129,438 0.60000-0.70000 130,339
' 1503238553-1717986917 149,886 0.70000-0.80000 150,000
' 1717986918-1932735282 170,338 0.80000-0.90000 170,128
' 1932735283-2147483647 189,548 0.90000-1.00000 190,347
Remarks
Random.Next generates a random number whose value ranges from 0 to less than Int32.MaxValue. To generate a random number whose value ranges from 0 to some other positive number, use the Random.Next(Int32) method overload. To generate a random number within a different range, use the Random.Next(Int32, Int32) method overload.
Notes to Inheritors
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 Next() 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 Next() method.
See also
Applies to
Next(Int32)
- Source:
- Random.cs
- Source:
- Random.cs
- Source:
- Random.cs
Returns a non-negative random integer that is less than the specified maximum.
public:
virtual int Next(int maxValue);
public virtual int Next (int maxValue);
abstract member Next : int -> int
override this.Next : int -> int
Public Overridable Function Next (maxValue As Integer) As Integer
Parameters
- maxValue
- Int32
The exclusive upper bound of the random number to be generated. maxValue
must be greater than or equal to 0.
Returns
A 32-bit signed integer that is greater than or equal to 0, and less than maxValue
; that is, the range of return values ordinarily includes 0 but not maxValue
. However, if maxValue
equals 0, 0 is returned.
Exceptions
maxValue
is less than 0.
Examples
The following example generates random integers with various overloads of the Next method.
// Example of the Random::Next() methods.
using namespace System;
// Generate random numbers with no bounds specified.
void NoBoundsRandoms(int seed)
{
Console::WriteLine("\nRandom object, seed = {0}, no bounds:", seed);
Random^ randObj = gcnew Random(seed);
// Generate six random integers from 0 to int.MaxValue.
for (int j = 0; j < 6; j++)
Console::Write("{0,11} ", randObj->Next());
Console::WriteLine();
}
// Generate random numbers with an upper bound specified.
void UpperBoundRandoms(int seed, int upper)
{
Console::WriteLine("\nRandom object, seed = {0}, upper bound = {1}:", seed, upper);
Random^ randObj = gcnew Random(seed);
// Generate six random integers from 0 to the upper bound.
for (int j = 0; j < 6; j++)
Console::Write("{0,11} ", randObj->Next(upper));
Console::WriteLine();
}
// Generate random numbers with both bounds specified.
void BothBoundsRandoms(int seed, int lower, int upper)
{
Console::WriteLine("\nRandom object, seed = {0}, lower = {1}, upper = {2}:", seed, lower, upper);
Random^ randObj = gcnew Random(seed);
// Generate six random integers from the lower to
// upper bounds.
for (int j = 0; j < 6; j++)
Console::Write("{0,11} ", randObj->Next(lower, upper));
Console::WriteLine();
}
int main()
{
Console::WriteLine("This example of the Random::Next() methods\n"
"generates the following output.\n");
Console::WriteLine("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.");
NoBoundsRandoms(234);
UpperBoundRandoms(234, Int32::MaxValue);
UpperBoundRandoms(234, 2000000000);
UpperBoundRandoms(234, 200000000);
BothBoundsRandoms(234, 0, Int32::MaxValue);
BothBoundsRandoms(234, Int32::MinValue, Int32::MaxValue);
BothBoundsRandoms(234, -2000000000, 2000000000);
BothBoundsRandoms(234, -200000000, 200000000);
BothBoundsRandoms(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
*/
Console.WriteLine(
"""
This example of the Random.Next() methods
generates the following output.
"""
);
Console.WriteLine(
"""
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.
"""
);
NoBoundsRandoms(234);
UpperBoundRandoms(234, int.MaxValue);
UpperBoundRandoms(234, 2000000000);
UpperBoundRandoms(234, 200000000);
BothBoundsRandoms(234, 0, int.MaxValue);
BothBoundsRandoms(234, int.MinValue, int.MaxValue);
BothBoundsRandoms(234, -2000000000, 2000000000);
BothBoundsRandoms(234, -200000000, 200000000);
BothBoundsRandoms(234, -2000, 2000);
// Generate random numbers with no bounds specified.
void NoBoundsRandoms(int seed)
{
Console.WriteLine(
$"\nRandom object, seed = {seed}, no bounds:"
);
Random randObj = new(seed);
// Generate six random integers from 0 to int.MaxValue.
for (int j = 0; j < 6; j++)
Console.Write($"{randObj.Next(),11} ");
Console.WriteLine();
}
// Generate random numbers with an upper bound specified.
void UpperBoundRandoms(int seed, int upper)
{
Console.WriteLine(
$"\nRandom object, seed = {seed}, upper bound = {upper}:"
);
Random randObj = new(seed);
// Generate six random integers from 0 to the upper bound.
for (int j = 0; j < 6; j++)
Console.Write($"{randObj.Next(upper),11} ");
Console.WriteLine();
}
// Generate random numbers with both bounds specified.
void BothBoundsRandoms(int seed, int lower, int upper)
{
Console.WriteLine(
"\nRandom object, seed = {0}, lower = {1}, " +
"upper = {2}:", seed, lower, upper);
Random randObj = new(seed);
// Generate six random integers from the lower to
// upper bounds.
for (int j = 0; j < 6; j++)
Console.Write($"{randObj.Next(lower, upper),11} ");
Console.WriteLine();
}
/*
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
*/
let noBoundsRandoms seed =
printfn "\nRandom object, seed = %i, no bounds:" seed
let randObj = Random seed
// Generate six random integers from 0 to int.MaxValue.
for _ = 1 to 6 do
printf $"%11i{randObj.Next()} "
printfn ""
// Generate random numbers with an upper bound specified.
let upperBoundRandoms seed upper =
printfn $"\nRandom object, seed = %i{seed}, upper bound = %i{upper}"
let randObj = Random seed
// Generate six random integers from 0 to the upper bound.
for _ = 1 to 6 do
printf $"%11i{randObj.Next upper} "
printfn ""
// Generate random numbers with both bounds specified.
let bothBoundRandoms seed lower upper =
printfn $"\nRandom object, seed = %i{seed}, lower = %i{lower}, upper = %i{upper}: "
let randObj = Random seed
// Generate six random integers from the lower to upper bounds.
for _ = 1 to 6 do
printf $"%11i{randObj.Next(lower,upper)} "
printfn ""
printfn "This example of the Random.Next() methods\ngenerates the following.\n"
printfn """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."""
noBoundsRandoms 234
upperBoundRandoms 234 Int32.MaxValue
upperBoundRandoms 234 2000000000
upperBoundRandoms 234 200000000
bothBoundRandoms 234 0 Int32.MaxValue
bothBoundRandoms 234 Int32.MinValue Int32.MaxValue
bothBoundRandoms 234 -2000000000 2000000000
bothBoundRandoms 234 -200000000 200000000
bothBoundRandoms 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
*)
' Example of the Random.Next() methods.
Module RandomNextDemo
' Generate random numbers with no bounds specified.
Sub NoBoundsRandoms(seed As Integer)
Console.WriteLine(vbCrLf &
"Random object, seed = {0}, no bounds:", seed)
Dim randObj As New Random(seed)
' Generate six random integers from 0 to int.MaxValue.
Dim j As Integer
For j = 0 To 5
Console.Write("{0,11} ", randObj.Next())
Next j
Console.WriteLine()
End Sub
' Generate random numbers with an upper bound specified.
Sub UpperBoundRandoms(seed As Integer, upper As Integer)
Console.WriteLine(vbCrLf &
"Random object, seed = {0}, upper bound = {1}:",
seed, upper)
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
Console.Write("{0,11} ", randObj.Next(upper))
Next j
Console.WriteLine()
End Sub
' Generate random numbers with both bounds specified.
Sub BothBoundsRandoms(seed As Integer, lower As Integer, upper As Integer)
Console.WriteLine(vbCrLf &
"Random object, seed = {0}, lower = {1}, " &
"upper = {2}:", seed, lower, upper)
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
Console.Write("{0,11} ",
randObj.Next(lower, upper))
Next j
Console.WriteLine()
End Sub
Sub Main()
Console.WriteLine(
"This example of the Random.Next() methods" &
vbCrLf & "generates the following output." & vbCrLf)
Console.WriteLine(
"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.")
NoBoundsRandoms(234)
UpperBoundRandoms(234, Int32.MaxValue)
UpperBoundRandoms(234, 2000000000)
UpperBoundRandoms(234, 200000000)
BothBoundsRandoms(234, 0, Int32.MaxValue)
BothBoundsRandoms(234, Int32.MinValue, Int32.MaxValue)
BothBoundsRandoms(234, -2000000000, 2000000000)
BothBoundsRandoms(234, -200000000, 200000000)
BothBoundsRandoms(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
The following example generates a random integer that it uses as an index to retrieve a string value from an array. Because the highest index of the array is one less than its length, the value of the Array.Length property is supplied as a the maxValue
parameter.
using namespace System;
void main()
{
Random^ rnd = gcnew Random();
array<String^>^ malePetNames = { "Rufus", "Bear", "Dakota", "Fido",
"Vanya", "Samuel", "Koani", "Volodya",
"Prince", "Yiska" };
array<String^>^ femalePetNames = { "Maggie", "Penny", "Saya", "Princess",
"Abby", "Laila", "Sadie", "Olivia",
"Starlight", "Talla" };
// Generate random indexes for pet names.
int mIndex = rnd->Next(malePetNames->Length);
int fIndex = rnd->Next(femalePetNames->Length);
// Display the result.
Console::WriteLine("Suggested pet name of the day: ");
Console::WriteLine(" For a male: {0}", malePetNames[mIndex]);
Console::WriteLine(" For a female: {0}", femalePetNames[fIndex]);
}
// The example displays output similar to the following:
// Suggested pet name of the day:
// For a male: Koani
// For a female: Maggie
Random rnd = new();
string[] malePetNames = [ "Rufus", "Bear", "Dakota", "Fido",
"Vanya", "Samuel", "Koani", "Volodya",
"Prince", "Yiska" ];
string[] femalePetNames = [ "Maggie", "Penny", "Saya", "Princess",
"Abby", "Laila", "Sadie", "Olivia",
"Starlight", "Talla" ];
// Generate random indexes for pet names.
int mIndex = rnd.Next(malePetNames.Length);
int fIndex = rnd.Next(femalePetNames.Length);
// Display the result.
Console.WriteLine("Suggested pet name of the day: ");
Console.WriteLine($" For a male: {malePetNames[mIndex]}");
Console.WriteLine($" For a female: {femalePetNames[fIndex]}");
// The example displays output similar to the following:
// Suggested pet name of the day:
// For a male: Koani
// For a female: Maggie
let rnd = Random()
let malePetNames =
[| "Rufus"; "Bear"; "Dakota"; "Fido";
"Vanya"; "Samuel"; "Koani"; "Volodya";
"Prince"; "Yiska" |]
let femalePetNames =
[| "Maggie"; "Penny"; "Saya"; "Princess";
"Abby"; "Laila"; "Sadie"; "Olivia";
"Starlight"; "Talla" |]
// Generate random indexes for pet names.
let mIndex = rnd.Next malePetNames.Length
let fIndex = rnd.Next femalePetNames.Length
// Display the result.
printfn "Suggested pet name of the day: "
printfn " For a male: %s" malePetNames.[mIndex]
printfn " For a female: %s" femalePetNames.[fIndex]
// The example displays output similar to the following:
// Suggested pet name of the day:
// For a male: Koani
// For a female: Maggie
Module Example
Public Sub Main()
Dim rnd As New Random()
Dim malePetNames() As String = { "Rufus", "Bear", "Dakota", "Fido",
"Vanya", "Samuel", "Koani", "Volodya",
"Prince", "Yiska" }
Dim femalePetNames() As String = { "Maggie", "Penny", "Saya", "Princess",
"Abby", "Laila", "Sadie", "Olivia",
"Starlight", "Talla" }
' Generate random indexes for pet names.
Dim mIndex As Integer = rnd.Next(malePetNames.Length)
Dim fIndex As Integer = rnd.Next(femalePetNames.Length)
' Display the result.
Console.WriteLine("Suggested pet name of the day: ")
Console.WriteLine(" For a male: {0}", malePetNames(mIndex))
Console.WriteLine(" For a female: {0}", femalePetNames(fIndex))
End Sub
End Module
' The example displays output similar to the following:
' Suggested pet name of the day:
' For a male: Koani
' For a female: Maggie
Remarks
The Next(Int32) overload returns random integers that range from 0 to maxValue
- 1. However, if maxValue
is 0, the method returns 0.
See also
Applies to
Next(Int32, Int32)
- Source:
- Random.cs
- Source:
- Random.cs
- Source:
- Random.cs
Returns a random integer that is within a specified range.
public:
virtual int Next(int minValue, int maxValue);
public virtual int Next (int minValue, int maxValue);
abstract member Next : int * int -> int
override this.Next : int * int -> int
Public Overridable Function Next (minValue As Integer, maxValue As Integer) As Integer
Parameters
- minValue
- Int32
The inclusive lower bound of the random number returned.
- maxValue
- Int32
The exclusive upper bound of the random number returned. maxValue
must be greater than or equal to minValue
.
Returns
A 32-bit signed integer greater than or equal to minValue
and less than maxValue
; that is, the range of return values includes minValue
but not maxValue
. If minValue
equals maxValue
, minValue
is returned.
Exceptions
minValue
is greater than maxValue
.
Examples
The following example uses the Random.Next(Int32, Int32) method to generate random integers with three distinct ranges. Note that the exact output from the example depends on the system-supplied seed value passed to the Random class constructor.
using namespace System;
void main()
{
Random^ rnd = gcnew Random();
Console::WriteLine("\n20 random integers from -100 to 100:");
for (int ctr = 1; ctr <= 20; ctr++)
{
Console::Write("{0,6}", rnd->Next(-100, 101));
if (ctr % 5 == 0) Console::WriteLine();
}
Console::WriteLine("\n20 random integers from 1000 to 10000:");
for (int ctr = 1; ctr <= 20; ctr++)
{
Console::Write("{0,8}", rnd->Next(1000, 10001));
if (ctr % 5 == 0) Console::WriteLine();
}
Console::WriteLine("\n20 random integers from 1 to 10:");
for (int ctr = 1; ctr <= 20; ctr++)
{
Console::Write("{0,6}", rnd->Next(1, 11));
if (ctr % 5 == 0) Console::WriteLine();
}
}
// The example displays output similar to the following:
// 20 random integers from -100 to 100:
// 65 -95 -10 90 -35
// -83 -16 -15 -19 41
// -67 -93 40 12 62
// -80 -95 67 -81 -21
//
// 20 random integers from 1000 to 10000:
// 4857 9897 4405 6606 1277
// 9238 9113 5151 8710 1187
// 2728 9746 1719 3837 3736
// 8191 6819 4923 2416 3028
//
// 20 random integers from 1 to 10:
// 9 8 5 9 9
// 9 1 2 3 8
// 1 4 8 10 5
// 9 7 9 10 5
Random rnd = new();
Console.WriteLine("\n20 random integers from -100 to 100:");
for (int ctr = 1; ctr <= 20; ctr++)
{
Console.Write("{0,6}", rnd.Next(-100, 101));
if (ctr % 5 == 0) Console.WriteLine();
}
Console.WriteLine("\n20 random integers from 1000 to 10000:");
for (int ctr = 1; ctr <= 20; ctr++)
{
Console.Write("{0,8}", rnd.Next(1000, 10001));
if (ctr % 5 == 0) Console.WriteLine();
}
Console.WriteLine("\n20 random integers from 1 to 10:");
for (int ctr = 1; ctr <= 20; ctr++)
{
Console.Write("{0,6}", rnd.Next(1, 11));
if (ctr % 5 == 0) Console.WriteLine();
}
// The example displays output similar to the following:
// 20 random integers from -100 to 100:
// 65 -95 -10 90 -35
// -83 -16 -15 -19 41
// -67 -93 40 12 62
// -80 -95 67 -81 -21
//
// 20 random integers from 1000 to 10000:
// 4857 9897 4405 6606 1277
// 9238 9113 5151 8710 1187
// 2728 9746 1719 3837 3736
// 8191 6819 4923 2416 3028
//
// 20 random integers from 1 to 10:
// 9 8 5 9 9
// 9 1 2 3 8
// 1 4 8 10 5
// 9 7 9 10 5
let rnd = Random()
printfn "\n20 random integers from -100 to 100:"
for i = 1 to 20 do
printf "%6i" (rnd.Next(-100,100))
if i % 5 = 0 then printfn ""
printfn "\n20 random integers from 1000 to 10000:"
for i = 1 to 20 do
printf "%8i" (rnd.Next(1000,10001))
if i % 5 = 0 then printfn ""
printfn "\n20 random integers from 1 to 10:"
for i = 1 to 20 do
printf "%6i" (rnd.Next(1,11))
if i % 5 = 0 then printfn ""
// The example displays output similar to the following:
// 20 random integers from -100 to 100:
// 65 -95 -10 90 -35
// -83 -16 -15 -19 41
// -67 -93 40 12 62
// -80 -95 67 -81 -21
//
// 20 random integers from 1000 to 10000:
// 4857 9897 4405 6606 1277
// 9238 9113 5151 8710 1187
// 2728 9746 1719 3837 3736
// 8191 6819 4923 2416 3028
//
// 20 random integers from 1 to 10:
// 9 8 5 9 9
// 9 1 2 3 8
// 1 4 8 10 5
// 9 7 9 10 5
Module Example
Public Sub Main()
Dim rnd As New Random()
Console.WriteLine("20 random integers from -100 to 100:")
For ctr As Integer = 1 To 20
Console.Write("{0,6}", rnd.Next(-100, 101))
If ctr Mod 5 = 0 Then Console.WriteLine()
Next
Console.WriteLine()
Console.WriteLine("20 random integers from 1000 to 10000:")
For ctr As Integer = 1 To 20
Console.Write("{0,8}", rnd.Next(1000, 10001))
If ctr Mod 5 = 0 Then Console.WriteLine()
Next
Console.WriteLine()
Console.WriteLine("20 random integers from 1 to 10:")
For ctr As Integer = 1 To 20
Console.Write("{0,6}", rnd.Next(1, 11))
If ctr Mod 5 = 0 Then Console.WriteLine()
Next
End Sub
End Module
' The example displays output similar to the following:
' 20 random integers from -100 to 100:
' 65 -95 -10 90 -35
' -83 -16 -15 -19 41
' -67 -93 40 12 62
' -80 -95 67 -81 -21
'
' 20 random integers from 1000 to 10000:
' 4857 9897 4405 6606 1277
' 9238 9113 5151 8710 1187
' 2728 9746 1719 3837 3736
' 8191 6819 4923 2416 3028
'
' 20 random integers from 1 to 10:
' 9 8 5 9 9
' 9 1 2 3 8
' 1 4 8 10 5
' 9 7 9 10 5
The following example generates a random integer that it uses as an index to retrieve a string value from an array. Because the highest index of the array is one less than its length, the value of the Array.Length property is supplied as a the maxValue
parameter.
using namespace System;
void main()
{
Random^ rnd = gcnew Random();
array<String^>^ malePetNames = { "Rufus", "Bear", "Dakota", "Fido",
"Vanya", "Samuel", "Koani", "Volodya",
"Prince", "Yiska" };
array<String^>^ femalePetNames = { "Maggie", "Penny", "Saya", "Princess",
"Abby", "Laila", "Sadie", "Olivia",
"Starlight", "Talla" };
// Generate random indexes for pet names.
int mIndex = rnd->Next(0, malePetNames->Length);
int fIndex = rnd->Next(0, femalePetNames->Length);
// Display the result.
Console::WriteLine("Suggested pet name of the day: ");
Console::WriteLine(" For a male: {0}", malePetNames[mIndex]);
Console::WriteLine(" For a female: {0}", femalePetNames[fIndex]);
}
// The example displays the following output:
// Suggested pet name of the day:
// For a male: Koani
// For a female: Maggie
Random rnd = new();
string[] malePetNames = [ "Rufus", "Bear", "Dakota", "Fido",
"Vanya", "Samuel", "Koani", "Volodya",
"Prince", "Yiska" ];
string[] femalePetNames = [ "Maggie", "Penny", "Saya", "Princess",
"Abby", "Laila", "Sadie", "Olivia",
"Starlight", "Talla" ];
// Generate random indexes for pet names.
int mIndex = rnd.Next(0, malePetNames.Length);
int fIndex = rnd.Next(0, femalePetNames.Length);
// Display the result.
Console.WriteLine("Suggested pet name of the day: ");
Console.WriteLine($" For a male: {malePetNames[mIndex]}");
Console.WriteLine($" For a female: {femalePetNames[fIndex]}");
// The example displays the following output:
// Suggested pet name of the day:
// For a male: Koani
// For a female: Maggie
let rnd = Random()
let malePetNames =
[| "Rufus"; "Bear"; "Dakota"; "Fido";
"Vanya"; "Samuel"; "Koani"; "Volodya";
"Prince"; "Yiska" |]
let femalePetNames =
[| "Maggie"; "Penny"; "Saya"; "Princess";
"Abby"; "Laila"; "Sadie"; "Olivia";
"Starlight"; "Talla" |]
// Generate random indexes for pet names.
let mIndex = rnd.Next(0, malePetNames.Length)
let fIndex = rnd.Next(0, femalePetNames.Length)
// Display the result.
printfn "Suggested pet name of the day: "
printfn " For a male: %s" malePetNames.[mIndex]
printfn " For a female: %s" femalePetNames.[fIndex]
// The example displays output similar to the following:
// Suggested pet name of the day:
// For a male: Koani
// For a female: Maggie
Module Example
Public Sub Main()
Dim rnd As New Random()
Dim malePetNames() As String = { "Rufus", "Bear", "Dakota", "Fido",
"Vanya", "Samuel", "Koani", "Volodya",
"Prince", "Yiska" }
Dim femalePetNames() As String = { "Maggie", "Penny", "Saya", "Princess",
"Abby", "Laila", "Sadie", "Olivia",
"Starlight", "Talla" }
' Generate random indexes for pet names.
Dim mIndex As Integer = rnd.Next(0, malePetNames.Length)
Dim fIndex As Integer = rnd.Next(0, femalePetNames.Length)
' Display the result.
Console.WriteLine("Suggested pet name of the day: ")
Console.WriteLine(" For a male: {0}", malePetNames(mIndex))
Console.WriteLine(" For a female: {0}", femalePetNames(fIndex))
End Sub
End Module
' The example displays output like the following:
' Suggested pet name of the day:
' For a male: Koani
' For a female: Maggie
Remarks
The Next(Int32, Int32) overload returns random integers that range from minValue
to maxValue
- 1. However, if maxValue
equals minValue
, the method returns minValue
.
Unlike the other overloads of the Next method, which return only non-negative values, this method can return a negative random integer.
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 Next(Int32, Int32) method overload if the difference between the minValue
and maxValue
parameters is greater than Int32.MaxValue. 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 Next(Int32, Int32) method overload.