Queryable.SkipWhile 方法

定義

只要指定的條件為 true,便略過序列中的項目,然後傳回其餘項目。Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.

多載

SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)

只要指定的條件為 true,便略過序列中的項目,然後傳回其餘項目。Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.

SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>)

只要指定的條件為 true,便略過序列中的項目,然後傳回其餘項目。Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. 項目的索引是用於述詞功能的邏輯中。The element's index is used in the logic of the predicate function.

SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)

只要指定的條件為 true,便略過序列中的項目,然後傳回其餘項目。Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.

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

類型參數

TSource

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

參數

source
IQueryable<TSource>

傳回項目的 IQueryable<T>An IQueryable<T> to return elements from.

predicate
Expression<Func<TSource,Boolean>>

用來測試每個項目是否符合條件的函式。A function to test each element for a condition.

傳回

IQueryable<TSource>

IQueryable<T>,其中包含的項目位於 source,而且是從沒有通過 predicate 所指定之測試的線性系列中第一個項目開始。An IQueryable<T> that contains elements from source starting at the first element in the linear series that does not pass the test specified by predicate.

例外狀況

sourcepredicatenullsource or predicate is null.

範例

下列程式碼範例示範如何使用 SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) 來略過陣列的元素(只要條件為 true)。The following code example demonstrates how to use SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) to skip elements of an array as long as a condition is true.

int[] grades = { 59, 82, 70, 56, 92, 98, 85 };

// Get all grades less than 80 by first
// sorting the grades in descending order and then
// taking all the grades after the first grade
// that is less than 80.
IEnumerable<int> lowerGrades =
    grades.AsQueryable()
    .OrderByDescending(grade => grade)
    .SkipWhile(grade => grade >= 80);

Console.WriteLine("All grades below 80:");
foreach (int grade in lowerGrades)
    Console.WriteLine(grade);

/*
    This code produces the following output:

    All grades below 80:
    70
    59
    56
*/
Dim grades() As Integer = {59, 82, 70, 56, 92, 98, 85}

' Get all grades less than 80 by first  sorting the grades 
' in descending order and then taking all the grades that 
' occur after the first grade that is less than 80.
Dim lowerGrades = grades.AsQueryable() _
    .OrderByDescending(Function(grade) grade) _
    .SkipWhile(Function(grade) grade >= 80)

Dim output As New System.Text.StringBuilder
output.AppendLine("All grades below 80:")
For Each grade As Integer In lowerGrades
    output.AppendLine(grade)
Next

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

' This code produces the following output:

' All grades below 80:
' 70
' 59
' 56

備註

這個方法至少有一個類型的參數 Expression<TDelegate> ,其型別引數是其中一種 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,並將其編譯為 Expression<TDelegate>For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)方法 MethodCallExpression 會產生,代表呼叫 SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) 本身做為已建立的泛型方法。The SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) method generates a MethodCallExpression that represents calling SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) itself as a constructed generic method. 然後,它會將傳遞 MethodCallExpression 給以 CreateQuery(Expression) 參數的屬性所表示的方法 IQueryProvider Provider sourceIt then passes the MethodCallExpression to the CreateQuery(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

執行表示呼叫的運算式樹狀架構所產生的查詢行為, SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) 取決於參數類型的實作為 sourceThe query behavior that occurs as a result of executing an expression tree that represents calling SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) depends on the implementation of the type of the source parameter. 預期的行為是它會套用 predicate 至中的每個專案, source 直到它找到會傳回 false 的元素為止 predicateThe expected behavior is that it applies predicate to each element in source until it finds an element for which predicate returns false. 系統會傳回該元素和所有其餘的元素。That element and all the remaining elements are returned.

適用於

SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>)

只要指定的條件為 true,便略過序列中的項目,然後傳回其餘項目。Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. 項目的索引是用於述詞功能的邏輯中。The element's index is used in the logic of the predicate function.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TSource> ^ SkipWhile(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, int, bool> ^> ^ predicate);
public static System.Linq.IQueryable<TSource> SkipWhile<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,int,bool>> predicate);
static member SkipWhile : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, int, bool>> -> System.Linq.IQueryable<'Source>
<Extension()>
Public Function SkipWhile(Of TSource) (source As IQueryable(Of TSource), predicate As Expression(Of Func(Of TSource, Integer, Boolean))) As IQueryable(Of TSource)

類型參數

TSource

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

參數

source
IQueryable<TSource>

傳回項目的 IQueryable<T>An IQueryable<T> to return elements from.

predicate
Expression<Func<TSource,Int32,Boolean>>

用來測試各項目是否符合條件的函式;此函式的第二個參數代表來源項目的索引。A function to test each element for a condition; the second parameter of this function represents the index of the source element.

傳回

IQueryable<TSource>

IQueryable<T>,其中包含的項目位於 source,而且是從沒有通過 predicate 所指定之測試的線性系列中第一個項目開始。An IQueryable<T> that contains elements from source starting at the first element in the linear series that does not pass the test specified by predicate.

例外狀況

sourcepredicatenullsource or predicate is null.

範例

下列程式碼範例示範如何使用 SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) 來略過陣列的元素,只要相依于元素索引的條件為 true 即可。The following code example demonstrates how to use SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) to skip elements of an array as long as a condition that depends on the element's index is true.

int[] amounts = { 5000, 2500, 9000, 8000,
                    6500, 4000, 1500, 5500 };

// Skip over amounts in the array until the first amount
// that is less than or equal to the product of its
// index in the array and 1000. Take the remaining items.
IEnumerable<int> query =
    amounts.AsQueryable()
    .SkipWhile((amount, index) => amount > index * 1000);

foreach (int amount in query)
    Console.WriteLine(amount);

/*
    This code produces the following output:

    4000
    1500
    5500
*/
Dim amounts() As Integer = {5000, 2500, 9000, 8000, _
                    6500, 4000, 1500, 5500}

' Skip over amounts in the array until the first amount
' that is less than or equal to the product of its
' index in the array and 1000. Take the remaining items.
Dim query = amounts.AsQueryable() _
    .SkipWhile(Function(amount, index) amount > index * 1000)

Dim output As New System.Text.StringBuilder
For Each amount As Integer In query
    output.AppendLine(amount)
Next

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

' This code produces the following output:

' 4000
' 1500
' 5500

備註

這個方法至少有一個類型的參數 Expression<TDelegate> ,其型別引數是其中一種 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,並將其編譯為 Expression<TDelegate>For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>)方法 MethodCallExpression 會產生,代表呼叫 SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) 本身做為已建立的泛型方法。The SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) method generates a MethodCallExpression that represents calling SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) itself as a constructed generic method. 然後,它會將傳遞 MethodCallExpression 給以 CreateQuery(Expression) 參數的屬性所表示的方法 IQueryProvider Provider sourceIt then passes the MethodCallExpression to the CreateQuery(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

執行表示呼叫的運算式樹狀架構所產生的查詢行為, SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) 取決於參數類型的實作為 sourceThe query behavior that occurs as a result of executing an expression tree that represents calling SkipWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) depends on the implementation of the type of the source parameter. 預期的行為是它會套用 predicate 至中的每個專案, source 直到它找到會傳回 false 的元素為止 predicateThe expected behavior is that it applies predicate to each element in source until it finds an element for which predicate returns false. 系統會傳回該元素和所有其餘的元素。That element and all the remaining elements are returned. 每個來源元素的索引都會作為的第二個引數提供 predicateThe index of each source element is provided as the second argument to predicate.

適用於