Random.Next Metod

Definition

Namnområde:
System
Sammansättningar:
mscorlib.dll, System.Runtime.Extensions.dll
Sammansättningar:
netstandard.dll, System.Runtime.dll
Sammansättning:
System.Runtime.Extensions.dll
Sammansättning:
mscorlib.dll
Sammansättning:
netstandard.dll

Returnerar ett slumpmässigt heltal.

Överlagringar

Name Description
Next(Int32)

Returnerar ett icke-negativt slumpmässigt heltal som är mindre än det angivna maxvärdet.
Next(Int32, Int32)

Returnerar ett slumpmässigt heltal som ligger inom ett angivet intervall.
Next()

Returnerar ett slumpmässigt heltal som inte är negativt.

Next(Int32)

Källa:
Random.cs
Källa:
Random.cs
Källa:
Random.cs
Källa:
Random.cs
Källa:
Random.cs

Returnerar ett icke-negativt slumpmässigt heltal som är mindre än det angivna maxvärdet.

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

Parametrar

maxValue
Int32

Den exklusiva övre gränsen för det slumpmässiga tal som ska genereras. maxValue måste vara större än eller lika med 0.

Returer

Int32

Ett 32-bitars signerat heltal som är större än eller lika med 0, och mindre än maxValue; det vill: intervallet med returvärden innehåller vanligtvis 0 men inte maxValue. Men om maxValue är lika med 0 returneras 0.

Undantag

ArgumentOutOfRangeException

maxValue är mindre än 0.

Exempel

I följande exempel genereras slumpmässiga heltal med olika överlagringar av Next metoden.

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

I följande exempel genereras ett slumpmässigt heltal som används som ett index för att hämta ett strängvärde från en matris. Eftersom matrisens högsta index är ett mindre än dess längd anges värdet för Array.Length egenskapen som maxValue parameter.

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

Kommentarer

Överlagringen Next(Int32) returnerar slumpmässiga heltal som sträcker sig från 0 till maxValue - 1. Men om maxValue är 0 returnerar metoden 0.

Se även

Gäller för

Next(Int32, Int32)

Källa:
Random.cs
Källa:
Random.cs
Källa:
Random.cs
Källa:
Random.cs
Källa:
Random.cs

Returnerar ett slumpmässigt heltal som ligger inom ett angivet intervall.

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

Parametrar

minValue
Int32

Den inkluderande nedre gränsen för det slumpmässiga talet som returneras.

maxValue
Int32

Den exklusiva övre gränsen för det slumpmässiga talet som returneras. maxValue måste vara större än eller lika med minValue.

Returer

Int32

Ett 32-bitars signerat heltal som är större än eller lika minValue med och mindre än maxValue, dvs. intervallet med returvärden inkluderar minValue men inte maxValue. Om minValue är lika med returneras maxValueminValue .

Undantag

ArgumentOutOfRangeException

minValue är större än maxValue.

Exempel

I följande exempel används Random.Next(Int32, Int32) metoden för att generera slumpmässiga heltal med tre distinkta intervall. Observera att de exakta utdata från exemplet beror på det systembaserade startvärde som skickas till Random klasskonstruktorn.

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

I följande exempel genereras ett slumpmässigt heltal som används som ett index för att hämta ett strängvärde från en matris. Eftersom matrisens högsta index är ett mindre än dess längd anges värdet för Array.Length egenskapen som parameter maxValue .

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

Kommentarer

Överlagringen Next(Int32, Int32) returnerar slumpmässiga heltal som sträcker sig från minValue till maxValue - 1. Men om maxValue är lika med returnerar minValueminValuemetoden .

Till skillnad från andra överlagringar av Next metoden, som endast returnerar icke-negativa värden, kan den här metoden returnera ett negativt slumpmässigt heltal.

Anteckningar till arvingar

Från och med .NET Framework version 2.0, om du härleder en klass från Random och åsidosätter metoden Sample(), fördelningen som tillhandahålls av den härledda klassimplementeringen av metoden Sample() används inte i anrop till basklassimplementeringen av metoden Next(Int32, Int32) om skillnaden mellan parametrarna minValue och maxValue är större än Int32.MaxValue. I stället används den enhetliga fördelningen som returneras av basklassen Random . Det här beteendet förbättrar klassens övergripande prestanda Random . Om du vill ändra det här beteendet för att anropa Sample() metoden i den härledda klassen måste du också åsidosätta metodens Next(Int32, Int32) överlagring.

Se även

Gäller för

Next()

Källa:
Random.cs
Källa:
Random.cs
Källa:
Random.cs
Källa:
Random.cs
Källa:
Random.cs

Returnerar ett slumpmässigt heltal som inte är negativt.

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

Returer

Int32

Ett 32-bitars signerat heltal som är större än eller lika med 0 och mindre än Int32.MaxValue.

Exempel

I följande exempel görs upprepade anrop till Next metoden för att generera 10 slumpmässiga tal.

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

I följande exempel härleds en klass från Random för att generera en sekvens med slumpmässiga tal vars fördelning skiljer sig från den enhetliga fördelning som genereras av Sample metoden för basklassen. Den åsidosätter Sample metoden för att tillhandahålla fördelningen av slumpmässiga tal och åsidosätter Random.Next metoden för att använda serier med slumpmässiga tal.

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

Kommentarer

Random.Next genererar ett slumpmässigt tal vars värde sträcker sig från 0 till mindre än Int32.MaxValue. Om du vill generera ett slumpmässigt tal vars värde sträcker sig från 0 till något annat positivt tal använder du Random.Next(Int32) metodens överbelastning. Om du vill generera ett slumpmässigt tal inom ett annat intervall använder du metodens Random.Next(Int32, Int32) överlagring.

Anteckningar till arvingar

Om du härleder en klass från Random och åsidosätter Sample() metoden används inte fördelningen som tillhandahålls av metodens härledda klassimplementering Sample() i anrop till metodens Next() basklassimplementering. I stället används den enhetliga fördelningen som returneras av basklassen Random . Det här beteendet förbättrar klassens övergripande prestanda Random . Om du vill ändra det här beteendet för att anropa Sample() metoden i den härledda klassen måste du också åsidosätta Next() metoden.

Se även

Gäller för