HashCode Struktura

Definicja

Łączy kod skrótu dla wielu wartości w jeden kod skrótu.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
Dziedziczenie
HashCode

Uwagi

Za pomocą HashCode można połączyć wiele wartości (na przykład pól struktury lub klasy) w jeden kod skrótu.You can use HashCode to combine multiple values (for example, fields on a structure or class) into a single hash code. Ta struktura działa na jeden z dwóch sposobów:This structure operates in one of two ways:

  • Metody statyczne, które akceptują zestaw maksymalnie ośmiu wartości do połączenia.Static methods that accept a set of up to eight values to combine.
  • Dwie metody instancji, które działają w sposób przesyłania strumieniowego, akceptując wartości pojedynczo.Two instance methods that operate in a streaming fashion, accepting values one at a time.

Ostrzeżenie

Najlepszym rozwiązaniem jest uwzględnienie kodów skrótów jako szczegółów implementacji, ponieważ implementacja może ulec zmianie w różnych wersjach zestawu.It is best-practice to consider hash codes as an implementation detail, as the implementation may change across assembly versions. Nie przechowuj kodów skrótu utworzonych przez HashCode w serializowanych strukturach, na przykład na dysku.Do not store hash codes produced by HashCode in serialized structures, for example, on-disk. w HashCode jest używany statycznie zainicjowany losowo inicjator, aby wymusić to najlepsze rozwiązanie, co oznacza, że kody skrótów są deterministyczne tylko w zakresie procesu systemu operacyjnego.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.

Metody statyczneStatic Methods

Metody statyczne łączą domyślne kody skrótów zawierające maksymalnie osiem wartości.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.

Metody wystąpieńInstance Methods

Ważne

ToHashCode() musi być wywołana maksymalnie raz na wystąpienie klasy HashCode.ToHashCode() must be called at most once per instance of HashCode.

Metody instancji łączą kody skrótów zawierające więcej niż osiem wartości.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.

Metody wystąpienia łączą również kody skrótów tworzone przez określoną implementację IEqualityComparer<T>.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.

Struktura HashCode musi być przesyłana przez odwołanie do innych metod, ponieważ jest to typ wartości.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.

Metody

Add<T>(T)

Dodaje pojedynczą wartość do kodu skrótu.Adds a single value to the hash code.

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

Dodaje pojedynczą wartość do kodu skrótu, określając typ, który dostarcza funkcję kodu skrótu.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)

Łączy osiem wartości w kod skrótu.Combines eight values into a hash code.

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

Łączy siedem wartości w kod skrótu.Combines seven values into a hash code.

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

Łączy sześć wartości w kod skrótu.Combines six values into a hash code.

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

Łączy pięć wartości w kod skrótu.Combines five values into a hash code.

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

Łączy cztery wartości w kod skrótu.Combines four values into a hash code.

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

Łączy trzy wartości w kod skrótu.Combines three values into a hash code.

Combine<T1,T2>(T1, T2)

Łączy dwie wartości w kod skrótu.Combines two values into a hash code.

Combine<T1>(T1)

Rozprasza kod skrótu zwrócony przez określoną wartość.Diffuses the hash code returned by the specified value.

Equals(Object)

Ta metoda nie jest obsługiwana i nie powinna być wywoływana.This method is not supported and should not be called.

GetHashCode()

Ta metoda nie jest obsługiwana i nie powinna być wywoływana.This method is not supported and should not be called.

ToHashCode()

Oblicza końcowy kod skrótu po kolejnych Add wywołaniach.Calculates the final hash code after consecutive Add invocations.

Dotyczy