Enumerable.SequenceEqual Metode

Definisi

Ruang nama:

System.Linq

Rakitan:

System.Linq.dll

Menentukan apakah dua urutan sama menurut perbandingan kesetaraan.

Overload

SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)	Menentukan apakah dua urutan sama dengan membandingkan elemen dengan menggunakan perbandingan kesetaraan default untuk jenisnya.
SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)	Menentukan apakah dua urutan sama dengan membandingkan elemennya dengan menggunakan IEqualityComparer<T>.

SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)

Sumber:

SequenceEqual.cs

Menentukan apakah dua urutan sama dengan membandingkan elemen dengan menggunakan perbandingan kesetaraan default untuk jenisnya.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static bool SequenceEqual(System::Collections::Generic::IEnumerable<TSource> ^ first, System::Collections::Generic::IEnumerable<TSource> ^ second);

public static bool SequenceEqual<TSource> (this System.Collections.Generic.IEnumerable<TSource> first, System.Collections.Generic.IEnumerable<TSource> second);

static member SequenceEqual : seq<'Source> * seq<'Source> -> bool

<Extension()>
Public Function SequenceEqual(Of TSource) (first As IEnumerable(Of TSource), second As IEnumerable(Of TSource)) As Boolean

Jenis parameter

TSource

Jenis elemen urutan input.

Parameter

first

IEnumerable<TSource>

Untuk IEnumerable<T> dibandingkan dengan second.

second

IEnumerable<TSource>

Untuk IEnumerable<T> membandingkan dengan urutan pertama.

Mengembalikan

Boolean

true jika kedua urutan sumber memiliki panjang yang sama dan elemen yang sesuai sama sesuai dengan perbandingan kesetaraan default untuk jenisnya; jika tidak, false.

Pengecualian

ArgumentNullException

first atau second adalah null.

Contoh

Contoh kode berikut menunjukkan cara menggunakan SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) untuk menentukan apakah dua urutan sama. Dalam dua contoh pertama, metode menentukan apakah urutan yang dibandingkan berisi referensi ke objek yang sama. Dalam contoh ketiga dan keempat, metode membandingkan data aktual objek dalam urutan.

Dalam contoh ini urutannya sama.

class Pet
{
    public string Name { get; set; }
    public int Age { get; set; }
}

public static void SequenceEqualEx1()
{
    Pet pet1 = new Pet { Name = "Turbo", Age = 2 };
    Pet pet2 = new Pet { Name = "Peanut", Age = 8 };

    // Create two lists of pets.
    List<Pet> pets1 = new List<Pet> { pet1, pet2 };
    List<Pet> pets2 = new List<Pet> { pet1, pet2 };

    bool equal = pets1.SequenceEqual(pets2);

    Console.WriteLine(
        "The lists {0} equal.",
        equal ? "are" : "are not");
}

/*
 This code produces the following output:

 The lists are equal.
*/

Class Pet
    Public Name As String
    Public Age As Integer
End Class

Sub SequenceEqualEx1()
    ' Create two Pet objects.
    Dim pet1 As New Pet With {.Name = "Turbo", .Age = 2}
    Dim pet2 As New Pet With {.Name = "Peanut", .Age = 8}

    ' Create two lists of pets.
    Dim pets1 As New List(Of Pet)(New Pet() {pet1, pet2})
    Dim pets2 As New List(Of Pet)(New Pet() {pet1, pet2})

    'Determine if the two lists are equal.
    Dim equal As Boolean = pets1.SequenceEqual(pets2)

    ' Display the output.
    Dim text As String = IIf(equal, "are", "are not")
    Console.WriteLine($"The lists {text} equal.")

End Sub

' This code produces the following output:
'
' The lists are equal.

Contoh kode berikut membandingkan dua urutan yang tidak sama. Perhatikan bahwa urutan berisi data yang identik, tetapi karena objek yang dikandungnya memiliki referensi yang berbeda, urutannya tidak dianggap sama.

class Pet
{
    public string Name { get; set; }
    public int Age { get; set; }
}

public static void SequenceEqualEx2()
{
    Pet pet1 = new Pet() { Name = "Turbo", Age = 2 };
    Pet pet2 = new Pet() { Name = "Peanut", Age = 8 };

    // Create two lists of pets.
    List<Pet> pets1 = new List<Pet> { pet1, pet2 };
    List<Pet> pets2 =
        new List<Pet> { new Pet { Name = "Turbo", Age = 2 },
                        new Pet { Name = "Peanut", Age = 8 } };

    bool equal = pets1.SequenceEqual(pets2);

    Console.WriteLine("The lists {0} equal.", equal ? "are" : "are not");
}

/*
 This code produces the following output:

 The lists are not equal.
*/

' Create two Pet objects.
Dim pet1 As New Pet With {.Name = "Turbo", .Age = 2}
Dim pet2 As New Pet With {.Name = "Peanut", .Age = 8}

' Create two lists of pets.
Dim pets1 As New List(Of Pet)()
pets1.Add(pet1)
pets1.Add(pet2)

Dim pets2 As New List(Of Pet)()
pets2.Add(New Pet With {.Name = "Turbo", .Age = 2})
pets2.Add(New Pet With {.Name = "Peanut", .Age = 8})

' Determine if the two lists are equal.
Dim equal As Boolean = pets1.SequenceEqual(pets2)

' Display the output.
Dim text As String = IIf(equal, "are", "are not")
Console.WriteLine($"The lists {text} equal.")

' This code produces the following output:
'
' The lists are not equal.

Jika Anda ingin membandingkan data aktual objek dalam urutan alih-alih hanya membandingkan referensinya, Anda harus mengimplementasikan IEqualityComparer<T> antarmuka generik di kelas Anda. Contoh kode berikut menunjukkan cara mengimplementasikan antarmuka ini di kelas pembantu dan menyediakan GetHashCode metode dan Equals .

public class ProductA : IEquatable<ProductA>
{
    public string Name { get; set; }
    public int Code { get; set; }

    public bool Equals(ProductA other)
    {
        if (other is null)
            return false;

        return this.Name == other.Name && this.Code == other.Code;
    }

    public override bool Equals(object obj) => Equals(obj as ProductA);
    public override int GetHashCode() => (Name, Code).GetHashCode();
}

Public Class ProductA
    Inherits IEquatable(Of ProductA)

    Public Property Name As String
    Public Property Code As Integer

    Public Function Equals(ByVal other As ProductA) As Boolean
        If other Is Nothing Then Return False
        Return Me.Name = other.Name AndAlso Me.Code = other.Code
    End Function

    Public Overrides Function Equals(ByVal obj As Object) As Boolean
        Return Equals(TryCast(obj, ProductA))
    End Function

    Public Overrides Function GetHashCode() As Integer
        Return (Name, Code).GetHashCode()
    End Function

End Class

Setelah menerapkan antarmuka ini, Anda dapat menggunakan urutan ProductA objek dalam SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) metode , seperti yang ditunjukkan dalam contoh berikut:

ProductA[] storeA = { new ProductA { Name = "apple", Code = 9 },
                       new ProductA { Name = "orange", Code = 4 } };

ProductA[] storeB = { new ProductA { Name = "apple", Code = 9 },
                       new ProductA { Name = "orange", Code = 4 } };

bool equalAB = storeA.SequenceEqual(storeB);

Console.WriteLine("Equal? " + equalAB);

/*
    This code produces the following output:

    Equal? True
*/

Dim storeA() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}}

Dim storeB() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}}

Dim equalAB = storeA.SequenceEqual(storeB)

Console.WriteLine("Equal? " & equalAB)

' This code produces the following output:

' Equal? True

Keterangan

Metode menghitung SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) dua urutan sumber secara paralel dan membandingkan elemen yang sesuai dengan menggunakan perbandingan kesetaraan default untuk TSource, Default.

Perbandingan kesetaraan default, Default, digunakan untuk membandingkan nilai jenis. Untuk membandingkan jenis data kustom, Anda perlu mengambil Equals alih metode dan GetHashCode , dan secara opsional mengimplementasikan IEquatable<T> antarmuka generik dalam jenis kustom. Untuk informasi selengkapnya, lihat Default properti.

SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)

Sumber:

SequenceEqual.cs

Menentukan apakah dua urutan sama dengan membandingkan elemennya dengan menggunakan IEqualityComparer<T>.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static bool SequenceEqual(System::Collections::Generic::IEnumerable<TSource> ^ first, System::Collections::Generic::IEnumerable<TSource> ^ second, System::Collections::Generic::IEqualityComparer<TSource> ^ comparer);

public static bool SequenceEqual<TSource> (this System.Collections.Generic.IEnumerable<TSource> first, System.Collections.Generic.IEnumerable<TSource> second, System.Collections.Generic.IEqualityComparer<TSource>? comparer);

static member SequenceEqual : seq<'Source> * seq<'Source> * System.Collections.Generic.IEqualityComparer<'Source> -> bool

<Extension()>
Public Function SequenceEqual(Of TSource) (first As IEnumerable(Of TSource), second As IEnumerable(Of TSource), comparer As IEqualityComparer(Of TSource)) As Boolean

Jenis parameter

TSource

Jenis elemen urutan input.

Parameter

first

IEnumerable<TSource>

Untuk IEnumerable<T> dibandingkan dengan second.

second

IEnumerable<TSource>

Untuk IEnumerable<T> membandingkan dengan urutan pertama.

comparer

IEqualityComparer<TSource>

Yang IEqualityComparer<T> digunakan untuk membandingkan elemen.

Mengembalikan

Boolean

true jika kedua urutan sumber memiliki panjang yang sama dan elemen yang sesuai dibandingkan dengan comparer; jika tidak, false.

Pengecualian

ArgumentNullException

first atau second adalah null.

Contoh

Contoh berikut menunjukkan cara mengimplementasikan perbandingan kesetaraan yang dapat digunakan dalam SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) metode .

public class Product
{
    public string Name { get; set; }
    public int Code { get; set; }
}

// Custom comparer for the Product class
class ProductComparer : IEqualityComparer<Product>
{
    // Products are equal if their names and product numbers are equal.
    public bool Equals(Product x, Product y)
    {

        //Check whether the compared objects reference the same data.
        if (Object.ReferenceEquals(x, y)) return true;

        //Check whether any of the compared objects is null.
        if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
            return false;

        //Check whether the products' properties are equal.
        return x.Code == y.Code && x.Name == y.Name;
    }

    // If Equals() returns true for a pair of objects
    // then GetHashCode() must return the same value for these objects.

    public int GetHashCode(Product product)
    {
        //Check whether the object is null
        if (Object.ReferenceEquals(product, null)) return 0;

        //Get hash code for the Name field if it is not null.
        int hashProductName = product.Name == null ? 0 : product.Name.GetHashCode();

        //Get hash code for the Code field.
        int hashProductCode = product.Code.GetHashCode();

        //Calculate the hash code for the product.
        return hashProductName ^ hashProductCode;
    }
}

Public Class Product
    Public Property Name As String
    Public Property Code As Integer
End Class

' Custom comparer for the Product class
Public Class ProductComparer
    Implements IEqualityComparer(Of Product)

    Public Function Equals1(
        ByVal x As Product, 
        ByVal y As Product
        ) As Boolean Implements IEqualityComparer(Of Product).Equals

        ' Check whether the compared objects reference the same data.
        If x Is y Then Return True

        'Check whether any of the compared objects is null.
        If x Is Nothing OrElse y Is Nothing Then Return False

        ' Check whether the products' properties are equal.
        Return (x.Code = y.Code) AndAlso (x.Name = y.Name)
    End Function

    Public Function GetHashCode1(
        ByVal product As Product
        ) As Integer Implements IEqualityComparer(Of Product).GetHashCode

        ' Check whether the object is null.
        If product Is Nothing Then Return 0

        ' Get hash code for the Name field if it is not null.
        Dim hashProductName = 
            If(product.Name Is Nothing, 0, product.Name.GetHashCode())

        ' Get hash code for the Code field.
        Dim hashProductCode = product.Code.GetHashCode()

        ' Calculate the hash code for the product.
        Return hashProductName Xor hashProductCode
    End Function
End Class

Setelah menerapkan perbandingan ini, Anda dapat menggunakan urutan Product objek dalam SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) metode , seperti yang ditunjukkan dalam contoh berikut:

Product[] storeA = { new Product { Name = "apple", Code = 9 },
                       new Product { Name = "orange", Code = 4 } };

Product[] storeB = { new Product { Name = "apple", Code = 9 },
                       new Product { Name = "orange", Code = 4 } };

bool equalAB = storeA.SequenceEqual(storeB, new ProductComparer());

Console.WriteLine("Equal? " + equalAB);

/*
    This code produces the following output:

    Equal? True
*/

Dim storeA() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}}

Dim storeB() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}}

Dim equalAB = storeA.SequenceEqual(storeB, New ProductComparer())

Console.WriteLine("Equal? " & equalAB)

' This code produces the following output:

' Equal? True

Keterangan

Metode menghitung SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) dua urutan sumber secara paralel dan membandingkan elemen yang sesuai dengan menggunakan yang ditentukan IEqualityComparer<T>. Jika comparer adalah null, perbandingan kesetaraan default, Default, digunakan untuk membandingkan elemen.