Queryable.TakeWhile Queryable.TakeWhile Queryable.TakeWhile Queryable.TakeWhile Method

定義

指定した条件が true の場合と、残りの要素をスキップし、限り、シーケンスから要素を返します。Returns elements from a sequence as long as a specified condition is true, and then skips the remaining elements.

オーバーロード

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

指定された条件が true の場合に限り、シーケンスから要素を返します。Returns elements from a sequence as long as a specified condition is true.

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

指定された条件が true の場合に限り、シーケンスから要素を返します。Returns elements from a sequence as long as a specified condition is true. 要素のインデックスは、述語関数のロジックで使用されます。The element's index is used in the logic of the predicate function.

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

指定された条件が true の場合に限り、シーケンスから要素を返します。Returns elements from a sequence as long as a specified condition is true.

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

型パラメーター

TSource

source の要素の型。The type of the elements of source.

パラメーター

source
IQueryable<TSource>

要素を返すシーケンス。The sequence to return elements from.

predicate
Expression<Func<TSource,Boolean>>

各要素が条件を満たしているかどうかをテストする関数。A function to test each element for a condition.

戻り値

IQueryable<TSource>

IQueryable<T>要素の位置によって指定されたテストの前に発生している入力シーケンスから要素を含むpredicateは渡さなくなりました。An IQueryable<T> that contains elements from the input sequence occurring before the element at which the test specified by predicate no longer passes.

例外

source または predicatenull です。source or predicate is null.

次のコード例は、使用する方法を示しますTakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)を条件が true であれば、シーケンスの先頭から要素を返します。The following code example demonstrates how to use TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) to return elements from the start of a sequence as long as a condition is true.

string[] fruits = { "apple", "banana", "mango", "orange", 
                      "passionfruit", "grape" };

// Take strings from the array until a string
// that is equal to "orange" is found.
IEnumerable<string> query =
    fruits.AsQueryable()
    .TakeWhile(fruit => String.Compare("orange", fruit, true) != 0);

foreach (string fruit in query)
    Console.WriteLine(fruit);

/*
    This code produces the following output:

    apple
    banana
    mango
*/

Dim fruits() As String = {"apple", "banana", "mango", "orange", _
                      "passionfruit", "grape"}

' Take strings from the array until a string
' that is equal to "orange" is found.
Dim query = fruits.AsQueryable() _
    .TakeWhile(Function(fruit) String.Compare("orange", fruit, True) <> 0)

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

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

'This code produces the following output:

'apple
'banana
'mango

注釈

このメソッドは、少なくとも 1 つのパラメーター型のExpression<TDelegate>型引数は、のいずれか、Func<T,TResult>型。This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. ラムダ式で、これらのパラメーターを渡すことができますにコンパイルされると、Expression<TDelegate>します。For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)メソッドを生成、MethodCallExpression呼び出しを表すTakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)として構築されたジェネリック メソッド自体。The TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) method generates a MethodCallExpression that represents calling TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) itself as a constructed generic method. これは、後、渡します、MethodCallExpressionCreateQuery(Expression)のメソッド、IQueryProviderによって表される、Providerのプロパティ、sourceパラメーター。It then passes the MethodCallExpression to the CreateQuery(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

呼び出し元を表す式ツリーを実行した結果として発生するクエリの動作TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)の型の実装によって異なります、sourceパラメーター。The query behavior that occurs as a result of executing an expression tree that represents calling TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) depends on the implementation of the type of the source parameter. 想定される動作が適用されることpredicate内の各要素にsource対象の要素が見つかるまでpredicate返しますfalseします。The expected behavior is that it applies predicate to each element in source until it finds an element for which predicate returns false. その時点までは、すべての要素を返します。It returns all the elements up until that point.

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

指定された条件が true の場合に限り、シーケンスから要素を返します。Returns elements from a sequence as long as a specified condition is true. 要素のインデックスは、述語関数のロジックで使用されます。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> ^ TakeWhile(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, int, bool> ^> ^ predicate);
public static System.Linq.IQueryable<TSource> TakeWhile<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,int,bool>> predicate);
static member TakeWhile : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, int, bool>> -> System.Linq.IQueryable<'Source>
<Extension()>
Public Function TakeWhile(Of TSource) (source As IQueryable(Of TSource), predicate As Expression(Of Func(Of TSource, Integer, Boolean))) As IQueryable(Of TSource)

型パラメーター

TSource

source の要素の型。The type of the elements of source.

パラメーター

source
IQueryable<TSource>

要素を返すシーケンス。The sequence to return elements from.

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

各要素の条件をテストする関数関数の 2 番目のパラメーターは、ソース シーケンス内の要素のインデックスを表します。A function to test each element for a condition; the second parameter of the function represents the index of the element in the source sequence.

戻り値

IQueryable<TSource>

IQueryable<T>要素の位置によって指定されたテストの前に発生している入力シーケンスから要素を含むpredicateは渡さなくなりました。An IQueryable<T> that contains elements from the input sequence occurring before the element at which the test specified by predicate no longer passes.

例外

source または predicatenull です。source or predicate is null.

次のコード例は、使用する方法を示しますTakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>)を要素のインデックスを使用する条件が真である限り、シーケンスの先頭から要素を返します。The following code example demonstrates how to use TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) to return elements from the start of a sequence as long as a condition that uses the index of the element is true.

string[] fruits = { "apple", "passionfruit", "banana", "mango", 
                      "orange", "blueberry", "grape", "strawberry" };

// Take strings from the array until a string whose length
// is less than its index in the array is found.
IEnumerable<string> query =
    fruits.AsQueryable()
    .TakeWhile((fruit, index) => fruit.Length >= index);

foreach (string fruit in query)
    Console.WriteLine(fruit);

/*
    This code produces the following output:

    apple
    passionfruit
    banana
    mango
    orange
    blueberry
*/

Dim fruits() As String = _
    {"apple", "passionfruit", "banana", "mango", _
     "orange", "blueberry", "grape", "strawberry"}

' Take strings from the array until a string whose length
' is less than its index in the array is found.
Dim query = fruits.AsQueryable() _
    .TakeWhile(Function(fruit, index) fruit.Length >= index)

' Display the results.
Dim output As New System.Text.StringBuilder
For Each fruit As String In query
    output.AppendLine(fruit)
Next
MsgBox(output.ToString())

' This code produces the following output:

' apple
' passionfruit
' banana
' mango
' orange
' blueberry

注釈

このメソッドは、少なくとも 1 つのパラメーター型のExpression<TDelegate>型引数は、のいずれか、Func<T,TResult>型。This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. ラムダ式で、これらのパラメーターを渡すことができますにコンパイルされると、Expression<TDelegate>します。For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>)メソッドを生成、MethodCallExpression呼び出しを表すTakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>)として構築されたジェネリック メソッド自体。The TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) method generates a MethodCallExpression that represents calling TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) itself as a constructed generic method. これは、後、渡します、MethodCallExpressionCreateQuery(Expression)のメソッド、IQueryProviderによって表される、Providerのプロパティ、sourceパラメーター。It then passes the MethodCallExpression to the CreateQuery(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

呼び出し元を表す式ツリーを実行した結果として発生するクエリの動作TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>)の型の実装によって異なります、sourceパラメーター。The query behavior that occurs as a result of executing an expression tree that represents calling TakeWhile<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) depends on the implementation of the type of the source parameter. 想定される動作が適用されることpredicate内の各要素にsource対象の要素が見つかるまでpredicate返しますfalseします。The expected behavior is that it applies predicate to each element in source until it finds an element for which predicate returns false. その時点までは、すべての要素を返します。It returns all the elements up until that point. 各ソース要素のインデックスが 2 番目の引数として提供されるpredicateします。The index of each source element is provided as the second argument to predicate.

適用対象