Queryable.Max Queryable.Max Queryable.Max Queryable.Max Method

定義

多載

Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>) Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>) Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>) Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>)

對泛型 IQueryable<T> 的每個項目叫用投影函式,並傳回最大的結果值。Invokes a projection function on each element of a generic IQueryable<T> and returns the maximum resulting value.

Max<TSource>(IQueryable<TSource>) Max<TSource>(IQueryable<TSource>) Max<TSource>(IQueryable<TSource>) Max<TSource>(IQueryable<TSource>)

傳回泛型 IQueryable<T> 中的最大值。Returns the maximum value in a generic IQueryable<T>.

Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>) Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>) Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>) Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>)

對泛型 IQueryable<T> 的每個項目叫用投影函式,並傳回最大的結果值。Invokes a projection function on each element of a generic IQueryable<T> and returns the maximum resulting value.

public:
generic <typename TSource, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static TResult Max(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, TResult> ^> ^ selector);
public static TResult Max<TSource,TResult> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,TResult>> selector);
static member Max : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, 'Result>> -> 'Result
<Extension()>
Public Function Max(Of TSource, TResult) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, TResult))) As TResult

類型參數

TSource

source 項目的類型。The type of the elements of source.

TResult

selector 表示之函式所傳回值的型別。The type of the value returned by the function represented by selector.

參數

source
IQueryable<TSource>

要判斷最大值的值序列。A sequence of values to determine the maximum of.

selector
Expression<Func<TSource,TResult>>

要套用到每個項目的投影函式。A projection function to apply to each element.

傳回

TResult TResult TResult TResult

序列中的最大值。The maximum value in the sequence.

例外狀況

sourceselectornullsource or selector is null.

範例

下列程式碼範例示範如何使用Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>)來判斷預測值序列中的最大值。The following code example demonstrates how to use Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>) to determine the maximum value in a sequence of projected values.

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

public static void MaxEx2()
{
    Pet[] pets = { new Pet { Name="Barley", Age=8 },
                   new Pet { Name="Boots", Age=4 },
                   new Pet { Name="Whiskers", Age=1 } };

    // Add Pet.Age to the length of Pet.Name
    // to determine the "maximum" Pet object in the array.
    int max =
        pets.AsQueryable().Max(pet => pet.Age + pet.Name.Length);

    Console.WriteLine(
        "The maximum pet age plus name length is {0}.",
        max);
}

/*
    This code produces the following output:

    The maximum pet age plus name length is 14.
*/

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

Shared Sub MaxEx2()
    Dim pets() As Pet = {New Pet With {.Name = "Barley", .Age = 8}, _
                   New Pet With {.Name = "Boots", .Age = 4}, _
                   New Pet With {.Name = "Whiskers", .Age = 1}}

    ' Add Pet.Age to the length of Pet.Name
    ' to determine the "maximum" Pet object in the array.
    Dim max As Integer = _
        pets.AsQueryable().Max(Function(pet) pet.Age + pet.Name.Length)

    MsgBox(String.Format("The maximum pet age plus name length is {0}.", max))

    'This code produces the following output:

    'The maximum pet age plus name length is 14.

備註

這個方法至少有一個類型Expression<TDelegate>的參數, 其類型引數是其中一個Func<T,TResult>類型。This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. 針對這些參數, 您可以傳入 lambda 運算式, 它會編譯成Expression<TDelegate>For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

方法會產生, 其代表以Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>)結構化泛型方法的方式呼叫本身。 MethodCallExpression Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>)The Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>) method generates a MethodCallExpression that represents calling Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>) itself as a constructed generic method. 然後, 它會MethodCallExpression將傳遞Execute<TResult>(Expression)至由Provider source參數IQueryProvider的屬性所表示之的方法。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

因執行代表呼叫Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>)之運算式樹狀架構而產生的查詢行為, 取決於source參數類型的實作為。The query behavior that occurs as a result of executing an expression tree that represents calling Max<TSource,TResult>(IQueryable<TSource>, Expression<Func<TSource,TResult>>) depends on the implementation of the type of the source parameter. 預期的行為是它selector會在中的每個元素上叫用source , 並傳回最大值。The expected behavior is that it invokes selector on each element in source and returns the maximum value.

Max<TSource>(IQueryable<TSource>) Max<TSource>(IQueryable<TSource>) Max<TSource>(IQueryable<TSource>) Max<TSource>(IQueryable<TSource>)

傳回泛型 IQueryable<T> 中的最大值。Returns the maximum value in a generic IQueryable<T>.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static TSource Max(System::Linq::IQueryable<TSource> ^ source);
public static TSource Max<TSource> (this System.Linq.IQueryable<TSource> source);
static member Max : System.Linq.IQueryable<'Source> -> 'Source
<Extension()>
Public Function Max(Of TSource) (source As IQueryable(Of TSource)) As TSource

類型參數

TSource

source 項目的類型。The type of the elements of source.

參數

source
IQueryable<TSource>

要判斷最大值的值序列。A sequence of values to determine the maximum of.

傳回

TSource TSource TSource TSource

序列中的最大值。The maximum value in the sequence.

例外狀況

範例

下列程式碼範例示範如何使用Max<TSource>(IQueryable<TSource>)來判斷序列中的最大值。The following code example demonstrates how to use Max<TSource>(IQueryable<TSource>) to determine the maximum value in a sequence.

List<long> longs = new List<long> { 4294967296L, 466855135L, 81125L };

long max = longs.AsQueryable().Max();

Console.WriteLine("The largest number is {0}.", max);

/*
    This code produces the following output:

    The largest number is 4294967296.
*/

Dim longs As New List(Of Long)(New Long() {4294967296L, 466855135L, 81125L})

Dim max As Long = longs.AsQueryable().Max()

MsgBox(String.Format("The largest number is {0}.", max))

'This code produces the following output:

'The largest number is 4294967296.

備註

方法會產生, 其代表以Max<TSource>(IQueryable<TSource>)結構化泛型方法的方式呼叫本身。 MethodCallExpression Max<TSource>(IQueryable<TSource>)The Max<TSource>(IQueryable<TSource>) method generates a MethodCallExpression that represents calling Max<TSource>(IQueryable<TSource>) itself as a constructed generic method. 然後, 它會MethodCallExpression將傳遞Execute<TResult>(Expression)至由Provider source參數IQueryProvider的屬性所表示之的方法。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

因執行代表呼叫Max<TSource>(IQueryable<TSource>)之運算式樹狀架構而產生的查詢行為, 取決於source參數類型的實作為。The query behavior that occurs as a result of executing an expression tree that represents calling Max<TSource>(IQueryable<TSource>) depends on the implementation of the type of the source parameter. 預期的行為是它會傳回中source的最大值。The expected behavior is that it returns the maximum value in source.

適用於