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Random.Next Metodo

  • Riferimento

Definizione

Spazio dei nomi:
System
Assembly:
System.Runtime.Extensions.dll
Assembly:
System.Runtime.dll
Assembly:
mscorlib.dll
Assembly:
netstandard.dll

Restituisce un intero casuale.

Overload

Next()

Restituisce un intero casuale non negativo.
Next(Int32)

Restituisce un intero casuale non negativo inferiore al massimo specificato.
Next(Int32, Int32)

Restituisce un numero intero casuale all'interno di un intervallo specificato.

Next()

Origine:
Random.cs
Origine:
Random.cs
Origine:
Random.cs

Restituisce un intero casuale non negativo.

public:
 virtual int Next();
public virtual int Next ();
abstract member Next : unit -> int
override this.Next : unit -> int
Public Overridable Function Next () As Integer

Restituisce

Int32

Intero con segno a 32 bit maggiore o uguale a 0 e minore di Int32.MaxValue.

Esempio

Nell'esempio riportato di seguito vengono effettuate chiamate ripetute al metodo Next per generare un numero specifico di numeri casuali richiesti dall'utente. Il metodo Console.ReadLine viene utilizzato per ricevere l'input del cliente.

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.Write("Number of random numbers to generate: ");

string? line = Console.ReadLine();
Random rnd = new Random();

if (!int.TryParse(line, out int numbers) || numbers <= 0)
{
    numbers = 10;
}

for (uint ctr = 1; ctr <= numbers; ctr++)
    Console.WriteLine($"{rnd.Next(),15:N0}");

// The example displays output like the following when asked to generate
// 15 random numbers:
// Number of random numbers to generate: 15
//     367 920 603
//   1 143 790 667
//   1 360 963 275
//   1 851 697 775
//     248 956 796
//   1 009 615 458
//   1 617 743 155
//   1 821 609 652
//   1 661 761 949
//     477 300 794
//     288 418 129
//     425 371 492
//   1 558 147 880
//   1 473 704 017
//     777 507 489

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

Nell'esempio seguente viene derivata una classe da Random per generare una sequenza di numeri casuali la cui distribuzione differisce dalla distribuzione uniforme generata dal Sample metodo della classe base. Esegue l'override del Sample metodo per fornire la distribuzione di numeri casuali e esegue l'override del Random.Next metodo per usare serie di numeri casuali.

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

Commenti

Random.Next genera un numero casuale il cui valore è compreso tra 0 e minore di Int32.MaxValue. Per generare un numero casuale il cui valore è compreso tra 0 e un altro numero positivo, usare l'overload del Random.Next(Int32) metodo. Per generare un numero casuale all'interno di un intervallo diverso, usare l'overload del Random.Next(Int32, Int32) metodo.

Note per gli eredi

A partire da .NET Framework versione 2.0, se si deriva una classe da Random e si esegue l'override del metodo, la distribuzione fornita dall'implementazione derivata del Sample() metodo non viene usata nelle chiamate all'implementazione Sample() della classe base del Next() metodo. Viene invece usata la distribuzione uniforme restituita dalla classe base Random . Questo comportamento migliora le prestazioni complessive della Random classe. Per modificare questo comportamento per chiamare il metodo nella classe derivata, è anche necessario eseguire l'override Sample() del Next() metodo.

Vedi anche

Si applica a

Next(Int32)

Origine:
Random.cs
Origine:
Random.cs
Origine:
Random.cs

Restituisce un intero casuale non negativo inferiore al massimo specificato.

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

Parametri

maxValue
Int32

Limite superiore esclusivo del numero casuale da generare. maxValue deve essere maggiore o uguale a 0.

Restituisce

Int32

Intero con segno a 32 bit maggiore o uguale a 0 e minore di maxValue; ovvero, l'intervallo dei valori restituiti in genere include 0 ma non maxValue. Tuttavia, se maxValue uguale a 0, viene restituito 0.

Eccezioni

ArgumentOutOfRangeException

maxValue è minore di 0.

Esempio

Nell'esempio seguente vengono generati numeri interi casuali con vari overload del Next metodo.

// 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

Nell'esempio seguente viene generato un intero casuale che usa come indice per recuperare un valore stringa da una matrice. Poiché l'indice più alto della matrice è minore della relativa lunghezza, il valore della Array.Length proprietà viene fornito come maxValue parametro.

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

Commenti

L'overload Next(Int32) restituisce numeri interi casuali compresi tra 0 e maxValue 1. Tuttavia, se maxValue è 0, il metodo restituisce 0.

Vedi anche

Si applica a

Next(Int32, Int32)

Origine:
Random.cs
Origine:
Random.cs
Origine:
Random.cs

Restituisce un numero intero casuale all'interno di un intervallo specificato.

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

Parametri

minValue
Int32

Limite inferiore inclusivo del numero casuale restituito.

maxValue
Int32

Limite superiore esclusivo del numero casuale restituito. maxValue deve essere maggiore o uguale a minValue.

Restituisce

Int32

Intero con segno a 32 bit maggiore o uguale a minValue e minore di maxValue: l'intervallo dei valori restituiti includerà minValue ma non maxValue. Se minValue è uguale a maxValue, viene restituito minValue.

Eccezioni

ArgumentOutOfRangeException

minValue è maggiore di maxValue.

Esempio

Nell'esempio seguente viene usato il Random.Next(Int32, Int32) metodo per generare interi casuali con tre intervalli distinti. Si noti che l'output esatto dell'esempio dipende dal valore di inizializzazione fornito dal sistema passato al costruttore della Random classe.

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

Nell'esempio seguente viene generato un intero casuale che usa come indice per recuperare un valore stringa da una matrice. Poiché l'indice più alto della matrice è minore della relativa lunghezza, il valore della Array.Length proprietà viene fornito come maxValue parametro.

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

Commenti

L'overload Next(Int32, Int32) restituisce numeri interi casuali compresi tra minValue - maxValue 1. Tuttavia, se maxValue è uguale a , il metodo restituisce minValueminValue.

A differenza degli altri overload del Next metodo, che restituiscono solo valori non negativi, questo metodo può restituire un intero casuale negativo.

Note per gli eredi

A partire da .NET Framework versione 2.0, se si deriva una classe da Random e si esegue l'override del metodo, la distribuzione fornita dall'implementazione derivata del Sample() metodo non viene usata nelle chiamate all'implementazione Sample() della classe base dell'overload Next(Int32, Int32) del metodo se la differenza tra i minValue parametri e maxValue è maggiore di Int32.MaxValue. Viene invece usata la distribuzione uniforme restituita dalla classe base Random . Questo comportamento migliora le prestazioni complessive della Random classe. Per modificare questo comportamento per chiamare il metodo nella classe derivata, è anche necessario eseguire l'override Sample() dell'overload del Next(Int32, Int32) metodo.

Vedi anche

Si applica a