# Enumerable.SequenceEqual 方法

## 重载

 SequenceEqual(IEnumerable, IEnumerable) 通过使用相应类型的默认相等比较器对序列的元素进行比较，以确定两个序列是否相等。Determines whether two sequences are equal by comparing the elements by using the default equality comparer for their type. SequenceEqual(IEnumerable, IEnumerable, IEqualityComparer) 通过使用指定的 IEqualityComparer 来比较两个序列的元素，以确定这两个序列是否相等。Determines whether two sequences are equal by comparing their elements by using a specified IEqualityComparer.

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

``````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``````

TSource

#### 参数

first
IEnumerable<TSource>

second
IEnumerable<TSource>

#### 例外

`first``second``null``first` or `second` is `null`.

### 示例

``````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.
``````

``````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)()

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.
``````

``````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
``````

``````
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
``````

### 注解

`SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)` 方法并行枚举两个源序列，并通过使用 `TSource`的默认相等比较器 Default来比较相应的元素。The `SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)` method enumerates the two source sequences in parallel and compares corresponding elements by using the default equality comparer for `TSource`, Default.

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

``````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``````

TSource

#### 参数

first
IEnumerable<TSource>

second
IEnumerable<TSource>

comparer
IEqualityComparer<TSource>

#### 例外

`first``second``null``first` or `second` is `null`.

### 示例

``````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
``````

``````
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
``````

### 注解

The SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) method enumerates the two source sequences in parallel and compares corresponding elements by using the specified IEqualityComparer<T>. 如果 `null``comparer`，则使用默认的相等比较器 Default来比较元素。If `comparer` is `null`, the default equality comparer, Default, is used to compare elements.