數量詞作業

更新：2007 年 11 月

數量詞作業會傳回 Boolean 值，指出序列中的部分或所有項目是否都符合條件。

下圖說明對兩個不同來源序列執行的兩個不同數量詞作業。第一個作業會問是否有一個或多個項目為字元 'A'，而結果是 true。第二個作業會問是否所有項目都是字元 'A'，而結果是 true。

下節會列出執行數量詞作業的標準查詢運算子方法。

方法

方法名稱	說明	C# 查詢運算式語法	Visual Basic 查詢運算式語法	詳細資訊
All	判斷序列中的項目是否全都符合條件。	不適用。	Aggregate … In … Into All(…)	Enumerable.All<TSource> Queryable.All<TSource>
Any	判斷序列中是否有任何項目會符合條件。	不適用。	Aggregate … In … Into Any()	Enumerable.Any Queryable.Any
Contains	判斷序列是否包含指定的項目。	不適用。	不適用。	Enumerable.Contains Queryable.Contains

查詢運算式語法範例

這些範例在 Visual Basic 中使用 Aggregate 子句，做為 LINQ 查詢中篩選條件的一部分。

下列範例使用 Aggregate 子句和 All<TSource> 擴充方法，以傳回集合中寵物年齡全都大於所指定年齡的人。

Class Person
    Private _name As String
    Private _pets As Pet()

    Public Property Name() As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property

    Public Property Pets() As Pet()
        Get
            Return _pets
        End Get
        Set(ByVal value As Pet())
            _pets = value
        End Set
    End Property
End Class

Class Pet
    Private _name As String
    Private _age As Integer

    Public Property Name() As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property

    Public Property Age() As Integer
        Get
            Return _age
        End Get
        Set(ByVal value As Integer)
            _age = value
        End Set
    End Property
End Class

Sub All()
    Dim barley As New Pet With {.Name = "Barley", .Age = 4}
    Dim boots As New Pet With {.Name = "Boots", .Age = 1}
    Dim whiskers As New Pet With {.Name = "Whiskers", .Age = 6}
    Dim bluemoon As New Pet With {.Name = "Blue Moon", .Age = 9}
    Dim daisy As New Pet With {.Name = "Daisy", .Age = 3}

    Dim charlotte As New Person With {.Name = "Charlotte", .Pets = New Pet() {barley, boots}}
    Dim arlene As New Person With {.Name = "Arlene", .Pets = New Pet() {whiskers}}
    Dim rui As New Person With {.Name = "Rui", .Pets = New Pet() {bluemoon, daisy}}

    ' Create the list of Person objects that will be queried.
    Dim people As New System.Collections.Generic.List(Of Person)(New Person() {charlotte, arlene, rui})

    Dim query = From pers In people _
                Where (Aggregate pt In pers.Pets Into All(pt.Age > 2)) _
                Select pers.Name

    Dim sb As New System.Text.StringBuilder()
    For Each name As String In query
        sb.AppendLine(name)
    Next

    ' Display the results.
    MsgBox(sb.ToString())

    ' This code produces the following output:

    ' Arlene
    ' Rui

End Sub

下一個範例使用 Aggregate 子句和 Any 擴充方法，以傳回集合中至少有一隻寵物年齡大於所指定年齡的人。

Class Person
    Private _name As String
    Private _pets As Pet()

    Public Property Name() As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property

    Public Property Pets() As Pet()
        Get
            Return _pets
        End Get
        Set(ByVal value As Pet())
            _pets = value
        End Set
    End Property
End Class

Class Pet
    Private _name As String
    Private _age As Integer

    Public Property Name() As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property

    Public Property Age() As Integer
        Get
            Return _age
        End Get
        Set(ByVal value As Integer)
            _age = value
        End Set
    End Property
End Class

Sub Any()
    Dim barley As New Pet With {.Name = "Barley", .Age = 4}
    Dim boots As New Pet With {.Name = "Boots", .Age = 1}
    Dim whiskers As New Pet With {.Name = "Whiskers", .Age = 6}
    Dim bluemoon As New Pet With {.Name = "Blue Moon", .Age = 9}
    Dim daisy As New Pet With {.Name = "Daisy", .Age = 3}

    Dim charlotte As New Person With {.Name = "Charlotte", .Pets = New Pet() {barley, boots}}
    Dim arlene As New Person With {.Name = "Arlene", .Pets = New Pet() {whiskers}}
    Dim rui As New Person With {.Name = "Rui", .Pets = New Pet() {bluemoon, daisy}}

    ' Create the list of Person objects that will be queried.
    Dim people As New System.Collections.Generic.List(Of Person)(New Person() {charlotte, arlene, rui})

    Dim query = From pers In people _
                Where (Aggregate pt In pers.Pets Into Any(pt.Age > 7)) _
                Select pers.Name

    Dim sb As New System.Text.StringBuilder()
    For Each name As String In query
        sb.AppendLine(name)
    Next

    ' Display the results.
    MsgBox(sb.ToString())

    ' This code produces the following output:

    ' Rui

End Sub

進一步了解如何執行量化作業

請參閱

工作

HOW TO：在執行階段動態指定述詞篩選條件 (C# 程式設計手冊)

概念

標準查詢運算子概觀

參考

Aggregate 子句 (Visual Basic)

System.Linq