Queryable.Except Method

Definition

Namespace:

System.Linq

Assembly:

System.Linq.Queryable.dll

Produces the set difference of two sequences.

Overloads

Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>)	Produces the set difference of two sequences by using the default equality comparer to compare values.
Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)	Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values.

Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>)

Source:

Queryable.cs

Produces the set difference of two sequences by using the default equality comparer to compare values.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TSource> ^ Except(System::Linq::IQueryable<TSource> ^ source1, System::Collections::Generic::IEnumerable<TSource> ^ source2);

public static System.Linq.IQueryable<TSource> Except<TSource> (this System.Linq.IQueryable<TSource> source1, System.Collections.Generic.IEnumerable<TSource> source2);

static member Except : System.Linq.IQueryable<'Source> * seq<'Source> -> System.Linq.IQueryable<'Source>

<Extension()>
Public Function Except(Of TSource) (source1 As IQueryable(Of TSource), source2 As IEnumerable(Of TSource)) As IQueryable(Of TSource)

Type Parameters

TSource

The type of the elements of the input sequences.

Parameters

source1

IQueryable<TSource>

An IQueryable<T> whose elements that are not also in source2 will be returned.

source2

IEnumerable<TSource>

An IEnumerable<T> whose elements that also occur in the first sequence will not appear in the returned sequence.

Returns

IQueryable<TSource>

An IQueryable<T> that contains the set difference of the two sequences.

Exceptions

ArgumentNullException

source1 or source2 is null.

Examples

The following code example demonstrates how to use Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>) to return those elements that only appear in the first source sequence.

double[] numbers1 = { 2.0, 2.1, 2.2, 2.3, 2.4, 2.5 };
double[] numbers2 = { 2.2 };

// Get the numbers from the first array that
// are NOT in the second array.
IEnumerable<double> onlyInFirstSet =
    numbers1.AsQueryable().Except(numbers2);

foreach (double number in onlyInFirstSet)
    Console.WriteLine(number);

/*
    This code produces the following output:

    2
    2.1
    2.3
    2.4
    2.5
*/

Dim numbers1() As Double = {2.0, 2.1, 2.2, 2.3, 2.4, 2.5}
Dim numbers2() As Double = {2.2}

' Get the numbers from the first array that
' are NOT in the second array.
Dim onlyInFirstSet As IEnumerable(Of Double) = _
    numbers1.AsQueryable().Except(numbers2)

Dim output As New System.Text.StringBuilder
For Each number As Double In onlyInFirstSet
    output.AppendLine(number)
Next

' Display the output.
MsgBox(output.ToString())

' This code produces the following output:
'
' 2
' 2.1
' 2.3
' 2.4
' 2.5

Remarks

The Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>) method generates a MethodCallExpression that represents calling Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>) itself as a constructed generic method. It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of thesource1 parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>) depends on the implementation of the type of the source1 parameter. The expected behavior is that all the elements in source1 are returned except for those that are also in source2.

Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)

Source:

Queryable.cs

Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TSource> ^ Except(System::Linq::IQueryable<TSource> ^ source1, System::Collections::Generic::IEnumerable<TSource> ^ source2, System::Collections::Generic::IEqualityComparer<TSource> ^ comparer);

public static System.Linq.IQueryable<TSource> Except<TSource> (this System.Linq.IQueryable<TSource> source1, System.Collections.Generic.IEnumerable<TSource> source2, System.Collections.Generic.IEqualityComparer<TSource>? comparer);

static member Except : System.Linq.IQueryable<'Source> * seq<'Source> * System.Collections.Generic.IEqualityComparer<'Source> -> System.Linq.IQueryable<'Source>

<Extension()>
Public Function Except(Of TSource) (source1 As IQueryable(Of TSource), source2 As IEnumerable(Of TSource), comparer As IEqualityComparer(Of TSource)) As IQueryable(Of TSource)

Type Parameters

TSource

The type of the elements of the input sequences.

Parameters

source1

IQueryable<TSource>

An IQueryable<T> whose elements that are not also in source2 will be returned.

source2

IEnumerable<TSource>

An IEnumerable<T> whose elements that also occur in the first sequence will not appear in the returned sequence.

comparer

IEqualityComparer<TSource>

An IEqualityComparer<T> to compare values.

Returns

IQueryable<TSource>

An IQueryable<T> that contains the set difference of the two sequences.

Exceptions

ArgumentNullException

source1 or source2 is null.

Remarks

The Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) method generates a MethodCallExpression that represents calling Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) itself as a constructed generic method. It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of thesource1 parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Except<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) depends on the implementation of the type of the source1 parameter. The expected behavior is that all the elements in source1 are returned except for those that are also in source2, and comparer is used to compare values.