HashCode HashCode HashCode HashCode Struct

Définition

Combine le code de hachage pour les valeurs multiples dans un code de hachage unique.Combines the hash code for multiple values into a single hash code.

public value class HashCode
public struct HashCode
type HashCode = struct
Public Structure HashCode
Héritage

Remarques

Vous pouvez utiliser HashCode pour combiner plusieurs valeurs (par exemple, les champs sur une structure ou classe) dans un code de hachage unique.You can use HashCode to combine multiple values (for example, fields on a structure or class) into a single hash code. Cette structure fonctionne dans un des deux manières :This structure operates in one of two ways:

  • Méthodes statiques qui acceptent une série de huit valeurs à combiner.Static methods that accept a set of up to eight values to combine.
  • Deux méthodes qui opèrent en flux continu, acceptant les valeurs 1 à la fois d’instance.Two instance methods that operate in a streaming fashion, accepting values one at a time.

Avertissement

Il est recommandée à prendre en compte les codes de hachage comme un détail d’implémentation, car l’implémentation peut changer entre les versions d’assembly.It is best-practice to consider hash codes as an implementation detail, as the implementation may change across assembly versions. Ne stockez pas les codes de hachage générés par HashCode dans des structures sérialisés, par exemple, sur le disque.Do not store hash codes produced by HashCode in serialized structures, for example, on-disk. HashCode utilise une valeur de départ aléatoire initialisée de manière statique pour appliquer cette meilleure pratique, ce qui signifie que les codes de hachage ne sont plus déterministes dans l’étendue d’un processus de système d’exploitation.HashCode uses a statically initialized random seed to enforce this best practice, meaning that the hash codes are only deterministic within the scope of an operating system process.

Méthodes statiquesStatic Methods

Les méthodes statiques combinent les codes de hachage par défaut des valeurs jusqu'à huit.The static methods combine the default hash codes of up to eight values.

using System;
using System.Collections.Generic;

public struct OrderOrderLine : IEquatable<OrderOrderLine>
{
    public int OrderId { get; }
    public int OrderLineId { get; }

    public OrderOrderLine(int orderId, int orderLineId) => (OrderId, OrderLineId) = (orderId, orderLineId);

    public override bool Equals(object obj) => obj is OrderOrderLine o && Equals(o);

    public bool Equals(OrderOrderLine other) => OrderId == other.OrderId && OrderLineId == other.OrderLineId;

    public override int GetHashCode() => HashCode.Combine(OrderId, OrderLineId);
}

class Program
{
    static void Main(string[] args)
    {
        var set = new HashSet<OrderOrderLine>
        {
            new OrderOrderLine(1, 1),
            new OrderOrderLine(1, 1),
            new OrderOrderLine(1, 2)
        };

        Console.WriteLine($"Item count: {set.Count}.");
    }
}
// The example displays the following output:
// Item count: 2.
Public Structure OrderOrderLine
    Implements IEquatable(Of OrderOrderLine)

    Public ReadOnly Property OrderId As Integer
    Public ReadOnly Property OrderLineId As Integer

    Public Sub New(ByVal orderId As Integer, ByVal orderLineId As Integer)
        Me.OrderId = orderId
        Me.OrderLineId = orderLineId
    End Sub

    Public Overrides Function Equals(obj As Object) As Boolean
        Return (TypeOf obj Is OrderOrderLine) AndAlso Equals(DirectCast(obj, OrderOrderLine))
    End Function

    Public Overloads Function Equals(other As OrderOrderLine) As Boolean Implements IEquatable(Of OrderOrderLine).Equals
        Return OrderId = other.OrderId AndAlso
               OrderLineId = other.OrderLineId
    End Function

    Public Overrides Function GetHashCode() As Integer
        Return HashCode.Combine(OrderId, OrderLineId)
    End Function

End Structure

Module Program

    Sub Main(args As String())
        Dim hashSet As HashSet(Of OrderOrderLine) = New HashSet(Of OrderOrderLine)
        hashSet.Add(New OrderOrderLine(1, 1))
        hashSet.Add(New OrderOrderLine(1, 1))
        hashSet.Add(New OrderOrderLine(1, 2))
        Console.WriteLine($"Item count: {hashSet.Count}")
    End Sub

End Module
' The example displays the following output:
' Item count: 2.

Méthodes d’instanceInstance Methods

Important

ToHashCode() doit être appelé au maximum une fois par instance de HashCode.ToHashCode() must be called at most once per instance of HashCode.

Les méthodes d’instance combinent les codes de hachage des valeurs de plus de huit.The instance methods combine the hash codes of more than eight values.

using System;
using System.Collections.Generic;

public struct Path : IEquatable<Path>
{
    public IReadOnlyList<string> Segments { get; }

    public Path(params string[] segments) => Segments = segments;

    public override bool Equals(object obj) => obj is Path o && Equals(o);

    public bool Equals(Path other)
    {
        if (ReferenceEquals(Segments, other.Segments)) return true;
        if (Segments is null || other.Segments is null) return false;
        if (Segments.Count != other.Segments.Count) return false;

        for (var i = 0; i < Segments.Count; i++)
        {
            if (!string.Equals(Segments[i], other.Segments[i]))
                return false;
        }

        return true;
    }

    public override int GetHashCode()
    {
        var hash = new HashCode();

        for (var i = 0; i < Segments?.Count; i++)
            hash.Add(Segments[i]);

        return hash.ToHashCode();
    }
}

class Program
{
    static void Main(string[] args)
    {
        var set = new HashSet<Path>
        {
            new Path("C:", "tmp", "file.txt"),
            new Path("C:", "tmp", "file.txt"),
            new Path("C:", "tmp", "file.tmp")
        };

        Console.WriteLine($"Item count: {set.Count}.");
    }
}
// The example displays the following output:
// Item count: 2.
Public Structure Path
    Implements IEquatable(Of Path)

    Public ReadOnly Property Segments As IReadOnlyList(Of String)

    Public Sub New(ParamArray ByVal segments() As String)
        Me.Segments = segments
    End Sub

    Public Overrides Function Equals(obj As Object) As Boolean
        Return (TypeOf obj Is Path) AndAlso Equals(DirectCast(obj, Path))
    End Function

    Public Overloads Function Equals(other As Path) As Boolean Implements IEquatable(Of Path).Equals
        If ReferenceEquals(Segments, other.Segments) Then Return True
        If Segments Is Nothing OrElse other.Segments Is Nothing Then Return False
        If Segments.Count <> other.Segments.Count Then Return False

        For i As Integer = 0 To Segments.Count - 1
            If Not String.Equals(Segments(i), other.Segments(i)) Then Return False
        Next

        Return True
    End Function

    Public Overrides Function GetHashCode() As Integer
        Dim hash As HashCode = New HashCode()

        For i As Integer = 0 To Segments?.Count - 1
            hash.Add(Segments(i))
        Next

        Return hash.ToHashCode()
    End Function

End Structure

Module Program

    Sub Main(args As String())
        Dim hashSet As HashSet(Of Path) = New HashSet(Of Path) From {
            New Path("C:", "tmp", "file.txt"),
            New Path("C:", "tmp", "file.txt"),
            New Path("C:", "tmp", "file.tmp")
        }
        Console.WriteLine($"Item count: {hashSet.Count}.")
    End Sub

End Module
' The example displays the following output:
' Item count: 2.

Les méthodes d’instance également combinent les codes de hachage générés par un spécifique IEqualityComparer<T> implémentation.The instance methods also combine the hash codes produced by a specific IEqualityComparer<T> implementation.

using System;
using System.Collections.Generic;

public struct Path : IEquatable<Path>
{
    public IReadOnlyList<string> Segments { get; }

    public Path(params string[] segments) => Segments = segments;

    public override bool Equals(object obj) => obj is Path o && Equals(o);

    public bool Equals(Path other)
    {
        if (ReferenceEquals(Segments, other.Segments)) return true;
        if (Segments is null || other.Segments is null) return false;
        if (Segments.Count != other.Segments.Count) return false;

        for (var i = 0; i < Segments.Count; i++)
        {
            if (!string.Equals(Segments[i], other.Segments[i], StringComparison.OrdinalIgnoreCase))
                return false;
        }

        return true;
    }

    public override int GetHashCode()
    {
        var hash = new HashCode();

        for (var i = 0; i < Segments?.Count; i++)
            hash.Add(Segments[i], StringComparer.OrdinalIgnoreCase);

        return hash.ToHashCode();
    }
}

class Program
{
    static void Main(string[] args)
    {
        var set = new HashSet<Path>
        {
            new Path("C:", "tmp", "file.txt"),
            new Path("C:", "TMP", "file.txt"),
            new Path("C:", "tmp", "FILE.TXT")
        };

        Console.WriteLine($"Item count: {set.Count}.");
    }
}
// The example displays the following output:
// Item count: 1.
Public Structure Path
    Implements IEquatable(Of Path)

    Public ReadOnly Property Segments As IReadOnlyList(Of String)

    Public Sub New(ParamArray ByVal segments() As String)
        Me.Segments = segments
    End Sub

    Public Overrides Function Equals(obj As Object) As Boolean
        Return (TypeOf obj Is Path) AndAlso Equals(DirectCast(obj, Path))
    End Function

    Public Overloads Function Equals(other As Path) As Boolean Implements IEquatable(Of Path).Equals
        If ReferenceEquals(Segments, other.Segments) Then Return True
        If Segments Is Nothing OrElse other.Segments Is Nothing Then Return False
        If Segments.Count <> other.Segments.Count Then Return False

        For i As Integer = 0 To Segments.Count - 1
            If Not String.Equals(Segments(i), other.Segments(i), StringComparison.OrdinalIgnoreCase) Then Return False
        Next

        Return True
    End Function

    Public Overrides Function GetHashCode() As Integer
        Dim hash As HashCode = New HashCode()

        For i As Integer = 0 To Segments?.Count - 1
            hash.Add(Segments(i), StringComparer.OrdinalIgnoreCase)
        Next

        Return hash.ToHashCode()
    End Function
    
End Structure

Module Program

    Sub Main(args As String())
        Dim hashSet As HashSet(Of Path) = New HashSet(Of Path) From {
            New Path("C:", "tmp", "file.txt"),
            New Path("C:", "TMP", "file.txt"),
            New Path("C:", "tmp", "FILE.TXT")
        }
        Console.WriteLine($"Item count: {hashSet.Count}.")
    End Sub

End Module
' The example displays the following output:
' Item count: 1.

Le HashCode structure transitent par référence à d’autres méthodes, car il s’agit d’un type valeur.The HashCode structure must be passed by-reference to other methods, as it is a value type.

using System;
using System.Collections.Generic;

public struct Path : IEquatable<Path>
{
    public IReadOnlyList<string> Segments { get; }

    public Path(params string[] segments) => Segments = segments;

    public override bool Equals(object obj) => obj is Path o && Equals(o);

    public bool Equals(Path other)
    {
        if (ReferenceEquals(Segments, other.Segments)) return true;
        if (Segments is null || other.Segments is null) return false;
        if (Segments.Count != other.Segments.Count) return false;

        for (var i = 0; i < Segments.Count; i++)
        {
            if (!PlatformUtils.PathEquals(Segments[i], other.Segments[i]))
                return false;
        }

        return true;
    }

    public override int GetHashCode()
    {
        var hash = new HashCode();

        for (var i = 0; i < Segments?.Count; i++)
            PlatformUtils.AddPath(ref hash, Segments[i]);

        return hash.ToHashCode();
    }
}

internal static class PlatformUtils
{
    public static bool PathEquals(string a, string b) => string.Equals(a, b, StringComparison.OrdinalIgnoreCase);
    public static void AddPath(ref HashCode hash, string path) => hash.Add(path, StringComparer.OrdinalIgnoreCase);
}

class Program
{
    static void Main(string[] args)
    {
        var set = new HashSet<Path>
        {
            new Path("C:", "tmp", "file.txt"),
            new Path("C:", "TMP", "file.txt"),
            new Path("C:", "tmp", "FILE.TXT")
        };

        Console.WriteLine($"Item count: {set.Count}.");
    }
}
// The example displays the following output:
// Item count: 1.
Public Structure Path
    Implements IEquatable(Of Path)

    Public ReadOnly Property Segments As IReadOnlyList(Of String)

    Public Sub New(ParamArray ByVal segments() As String)
        Me.Segments = segments
    End Sub

    Public Overrides Function Equals(obj As Object) As Boolean
        Return (TypeOf obj Is Path) AndAlso Equals(DirectCast(obj, Path))
    End Function

    Public Overloads Function Equals(other As Path) As Boolean Implements IEquatable(Of Path).Equals
        If ReferenceEquals(Segments, other.Segments) Then Return True
        If Segments Is Nothing OrElse other.Segments Is Nothing Then Return False
        If Segments.Count <> other.Segments.Count Then Return False

        For i As Integer = 0 To Segments.Count - 1
            If Not PathEquals(Segments(i), other.Segments(i)) Then Return False
        Next

        Return True
    End Function

    Public Overrides Function GetHashCode() As Integer
        Dim hash As HashCode = New HashCode()

        For i As Integer = 0 To Segments?.Count - 1
            AddPath(hash, Segments(i))
        Next

        Return hash.ToHashCode()
    End Function
    
End Structure

Friend Module PlatformUtils

    Public Function PathEquals(ByVal a As String, ByVal b As String) As Boolean
        Return String.Equals(a, b, StringComparison.OrdinalIgnoreCase)
    End Function

    Public Sub AddPath(ByRef hash As HashCode, ByVal path As String)
        hash.Add(path, StringComparer.OrdinalIgnoreCase)
    End Sub

End Module

Module Program

    Sub Main(args As String())
        Dim hashSet As HashSet(Of Path) = New HashSet(Of Path) From {
            New Path("C:", "tmp", "file.txt"),
            New Path("C:", "TMP", "file.txt"),
            New Path("C:", "tmp", "FILE.TXT")
        }
        Console.WriteLine($"Item count: {hashSet.Count}.")
    End Sub

End Module
' The example displays the following output:
' Item count: 1.

Méthodes

Add<T>(T) Add<T>(T) Add<T>(T) Add<T>(T)

Ajoute une valeur unique au code de hachage.Adds a single value to the hash code.

Add<T>(T, IEqualityComparer<T>) Add<T>(T, IEqualityComparer<T>) Add<T>(T, IEqualityComparer<T>) Add<T>(T, IEqualityComparer<T>)

Ajoute une valeur unique au code de hachage, en spécifiant le type qui fournit la fonction de code de hachage.Adds a single value to the hash code, specifying the type that provides the hash code function.

Combine<T1,T2,T3,T4,T5,T6,T7,T8>(T1, T2, T3, T4, T5, T6, T7, T8) Combine<T1,T2,T3,T4,T5,T6,T7,T8>(T1, T2, T3, T4, T5, T6, T7, T8) Combine<T1,T2,T3,T4,T5,T6,T7,T8>(T1, T2, T3, T4, T5, T6, T7, T8) Combine<T1,T2,T3,T4,T5,T6,T7,T8>(T1, T2, T3, T4, T5, T6, T7, T8)

Combine huit valeurs dans un code de hachage.Combines eight values into a hash code.

Combine<T1,T2,T3,T4,T5,T6,T7>(T1, T2, T3, T4, T5, T6, T7) Combine<T1,T2,T3,T4,T5,T6,T7>(T1, T2, T3, T4, T5, T6, T7) Combine<T1,T2,T3,T4,T5,T6,T7>(T1, T2, T3, T4, T5, T6, T7) Combine<T1,T2,T3,T4,T5,T6,T7>(T1, T2, T3, T4, T5, T6, T7)

Combine sept valeurs dans un code de hachage.Combines seven values into a hash code.

Combine<T1,T2,T3,T4,T5,T6>(T1, T2, T3, T4, T5, T6) Combine<T1,T2,T3,T4,T5,T6>(T1, T2, T3, T4, T5, T6) Combine<T1,T2,T3,T4,T5,T6>(T1, T2, T3, T4, T5, T6) Combine<T1,T2,T3,T4,T5,T6>(T1, T2, T3, T4, T5, T6)

Combine six valeurs dans un code de hachage.Combines six values into a hash code.

Combine<T1,T2,T3,T4,T5>(T1, T2, T3, T4, T5) Combine<T1,T2,T3,T4,T5>(T1, T2, T3, T4, T5) Combine<T1,T2,T3,T4,T5>(T1, T2, T3, T4, T5) Combine<T1,T2,T3,T4,T5>(T1, T2, T3, T4, T5)

Combine cinq valeurs dans un code de hachage.Combines five values into a hash code.

Combine<T1,T2,T3,T4>(T1, T2, T3, T4) Combine<T1,T2,T3,T4>(T1, T2, T3, T4) Combine<T1,T2,T3,T4>(T1, T2, T3, T4) Combine<T1,T2,T3,T4>(T1, T2, T3, T4)

Combine quatre valeurs dans un code de hachage.Combines four values into a hash code.

Combine<T1,T2,T3>(T1, T2, T3) Combine<T1,T2,T3>(T1, T2, T3) Combine<T1,T2,T3>(T1, T2, T3) Combine<T1,T2,T3>(T1, T2, T3)

Combine trois valeurs dans un code de hachage.Combines three values into a hash code.

Combine<T1,T2>(T1, T2) Combine<T1,T2>(T1, T2) Combine<T1,T2>(T1, T2) Combine<T1,T2>(T1, T2)

Combine deux valeurs dans un code de hachage.Combines two values into a hash code.

Combine<T1>(T1) Combine<T1>(T1) Combine<T1>(T1) Combine<T1>(T1)

Diffuse le code de hachage retourné par la valeur spécifiée.Diffuses the hash code returned by the specified value.

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Cette méthode n’est pas prise en charge et ne doit pas être appelée.This method is not supported and should not be called.

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Cette méthode n’est pas prise en charge et ne doit pas être appelée.This method is not supported and should not be called.

ToHashCode() ToHashCode() ToHashCode() ToHashCode()

Calcule le code de hachage final après des appels de Add consécutifs.Calculates the final hash code after consecutive Add invocations.

S’applique à