List<T>.RemoveAll(Predicate<T>) List<T>.RemoveAll(Predicate<T>) List<T>.RemoveAll(Predicate<T>) List<T>.RemoveAll(Predicate<T>) Method

定義

指定した述語によって定義される条件に一致するすべての要素を削除します。Removes all the elements that match the conditions defined by the specified predicate.

public:
 int RemoveAll(Predicate<T> ^ match);
public int RemoveAll (Predicate<T> match);
member this.RemoveAll : Predicate<'T> -> int
Public Function RemoveAll (match As Predicate(Of T)) As Integer

パラメーター

match
Predicate<T> Predicate<T> Predicate<T> Predicate<T>

削除する要素の条件を定義する Predicate<T> デリゲート。The Predicate<T> delegate that defines the conditions of the elements to remove.

戻り値

List<T> から削除される要素の数。The number of elements removed from the List<T>.

例外

次の例は、 RemoveAll Predicate<T>ジェネリックデリゲートを使用するメソッドとその他のいくつかのメソッドを示しています。The following example demonstrates the RemoveAll method and several other methods that use the Predicate<T> generic delegate.

文字列List<T>のが作成され、そのうちの2つ (位置1と 5) の末尾が "saurus" である8個の恐竜名が含まれます。A List<T> of strings is created, containing 8 dinosaur names, two of which (at positions 1 and 5) end with "saurus". また、この例では、文字列パラメーター EndsWithSaurusを受け取り、入力文字列が "saurus" で終わるかどうかを示すブール値を返すという名前の検索述語メソッドを定義しています。The example also defines a search predicate method named EndsWithSaurus, which accepts a string parameter and returns a Boolean value indicating whether the input string ends in "saurus".

FindFindLastおよびFindAllの各メソッドは、検索述語メソッドを使用してリストを検索するために使用されます。The Find, FindLast, and FindAll methods are used to search the list with the search predicate method.

メソッドRemoveAllは、"saurus" で終わるすべてのエントリを削除するために使用されます。The RemoveAll method is used to remove all entries ending with "saurus". 最初からリストを走査し、各要素をEndsWithSaurusメソッドに渡します。It traverses the list from the beginning, passing each element in turn to the EndsWithSaurus method. EndsWithSaurusメソッドがを返しtrueた場合、要素は削除されます。The element is removed if the EndsWithSaurus method returns true.

注意

およびC# Visual Basic では、 Predicate<string>デリゲート (Predicate(Of String) Visual Basic) を明示的に作成する必要はありません。In C# and Visual Basic, it is not necessary to create the Predicate<string> delegate (Predicate(Of String) in Visual Basic) explicitly. これらの言語は、コンテキストから正しいデリゲートを推測し、自動的に作成します。These languages infer the correct delegate from context, and create it automatically.

最後に、 Existsメソッドは、"saurus" で終わる文字列がリストにないことを確認します。Finally, the Exists method verifies that there are no strings in the list that end with "saurus".

using namespace System;
using namespace System::Collections::Generic;

// Search predicate returns true if a string ends in "saurus".
bool EndsWithSaurus(String^ s)
{
    return s->ToLower()->EndsWith("saurus");
};

void main()
{
    List<String^>^ dinosaurs = gcnew List<String^>();

    dinosaurs->Add("Compsognathus");
    dinosaurs->Add("Amargasaurus");
    dinosaurs->Add("Oviraptor");
    dinosaurs->Add("Velociraptor");
    dinosaurs->Add("Deinonychus");
    dinosaurs->Add("Dilophosaurus");
    dinosaurs->Add("Gallimimus");
    dinosaurs->Add("Triceratops");

    Console::WriteLine();
    for each(String^ dinosaur in dinosaurs )
    {
        Console::WriteLine(dinosaur);
    }

    Console::WriteLine("\nTrueForAll(EndsWithSaurus): {0}",
        dinosaurs->TrueForAll(gcnew Predicate<String^>(EndsWithSaurus)));

    Console::WriteLine("\nFind(EndsWithSaurus): {0}", 
        dinosaurs->Find(gcnew Predicate<String^>(EndsWithSaurus)));

    Console::WriteLine("\nFindLast(EndsWithSaurus): {0}",
        dinosaurs->FindLast(gcnew Predicate<String^>(EndsWithSaurus)));

    Console::WriteLine("\nFindAll(EndsWithSaurus):");
    List<String^>^ sublist = 
        dinosaurs->FindAll(gcnew Predicate<String^>(EndsWithSaurus));

    for each(String^ dinosaur in sublist)
    {
        Console::WriteLine(dinosaur);
    }

    Console::WriteLine(
        "\n{0} elements removed by RemoveAll(EndsWithSaurus).", 
        dinosaurs->RemoveAll(gcnew Predicate<String^>(EndsWithSaurus)));

    Console::WriteLine("\nList now contains:");
    for each(String^ dinosaur in dinosaurs)
    {
        Console::WriteLine(dinosaur);
    }

    Console::WriteLine("\nExists(EndsWithSaurus): {0}", 
        dinosaurs->Exists(gcnew Predicate<String^>(EndsWithSaurus)));
}

/* This code example produces the following output:

Compsognathus
Amargasaurus
Oviraptor
Velociraptor
Deinonychus
Dilophosaurus
Gallimimus
Triceratops

TrueForAll(EndsWithSaurus): False

Find(EndsWithSaurus): Amargasaurus

FindLast(EndsWithSaurus): Dilophosaurus

FindAll(EndsWithSaurus):
Amargasaurus
Dilophosaurus

2 elements removed by RemoveAll(EndsWithSaurus).

List now contains:
Compsognathus
Oviraptor
Velociraptor
Deinonychus
Gallimimus
Triceratops

Exists(EndsWithSaurus): False
 */
using System;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        List<string> dinosaurs = new List<string>();

        dinosaurs.Add("Compsognathus");
        dinosaurs.Add("Amargasaurus");
        dinosaurs.Add("Oviraptor");
        dinosaurs.Add("Velociraptor");
        dinosaurs.Add("Deinonychus");
        dinosaurs.Add("Dilophosaurus");
        dinosaurs.Add("Gallimimus");
        dinosaurs.Add("Triceratops");

        Console.WriteLine();
        foreach(string dinosaur in dinosaurs)
        {
            Console.WriteLine(dinosaur);
        }

        Console.WriteLine("\nTrueForAll(EndsWithSaurus): {0}",
            dinosaurs.TrueForAll(EndsWithSaurus));

        Console.WriteLine("\nFind(EndsWithSaurus): {0}", 
            dinosaurs.Find(EndsWithSaurus));

        Console.WriteLine("\nFindLast(EndsWithSaurus): {0}",
            dinosaurs.FindLast(EndsWithSaurus));

        Console.WriteLine("\nFindAll(EndsWithSaurus):");
        List<string> sublist = dinosaurs.FindAll(EndsWithSaurus);

        foreach(string dinosaur in sublist)
        {
            Console.WriteLine(dinosaur);
        }

        Console.WriteLine(
            "\n{0} elements removed by RemoveAll(EndsWithSaurus).", 
            dinosaurs.RemoveAll(EndsWithSaurus));

        Console.WriteLine("\nList now contains:");
        foreach(string dinosaur in dinosaurs)
        {
            Console.WriteLine(dinosaur);
        }

        Console.WriteLine("\nExists(EndsWithSaurus): {0}", 
            dinosaurs.Exists(EndsWithSaurus));
    }

    // Search predicate returns true if a string ends in "saurus".
    private static bool EndsWithSaurus(String s)
    {
        return s.ToLower().EndsWith("saurus");
    }
}

/* This code example produces the following output:

Compsognathus
Amargasaurus
Oviraptor
Velociraptor
Deinonychus
Dilophosaurus
Gallimimus
Triceratops

TrueForAll(EndsWithSaurus): False

Find(EndsWithSaurus): Amargasaurus

FindLast(EndsWithSaurus): Dilophosaurus

FindAll(EndsWithSaurus):
Amargasaurus
Dilophosaurus

2 elements removed by RemoveAll(EndsWithSaurus).

List now contains:
Compsognathus
Oviraptor
Velociraptor
Deinonychus
Gallimimus
Triceratops

Exists(EndsWithSaurus): False
 */
Imports System.Collections.Generic

Public Class Example

    Public Shared Sub Main()

        Dim dinosaurs As New List(Of String)

        dinosaurs.Add("Compsognathus")
        dinosaurs.Add("Amargasaurus")
        dinosaurs.Add("Oviraptor")
        dinosaurs.Add("Velociraptor")
        dinosaurs.Add("Deinonychus")
        dinosaurs.Add("Dilophosaurus")
        dinosaurs.Add("Gallimimus")
        dinosaurs.Add("Triceratops")

        Console.WriteLine()
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        Next

        Console.WriteLine(vbLf & _
            "TrueForAll(AddressOf EndsWithSaurus: {0}", _
            dinosaurs.TrueForAll(AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & _
            "Find(AddressOf EndsWithSaurus): {0}", _
            dinosaurs.Find(AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & _
            "FindLast(AddressOf EndsWithSaurus): {0}", _
            dinosaurs.FindLast(AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & _
            "FindAll(AddressOf EndsWithSaurus):")
        Dim sublist As List(Of String) = _
            dinosaurs.FindAll(AddressOf EndsWithSaurus)

        For Each dinosaur As String In sublist
            Console.WriteLine(dinosaur)
        Next

        Console.WriteLine(vbLf & _
            "{0} elements removed by RemoveAll(AddressOf EndsWithSaurus).", _
            dinosaurs.RemoveAll(AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & "List now contains:")
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        Next

        Console.WriteLine(vbLf & _
            "Exists(AddressOf EndsWithSaurus): {0}", _
            dinosaurs.Exists(AddressOf EndsWithSaurus))
        
    End Sub

    ' Search predicate returns true if a string ends in "saurus".
    Private Shared Function EndsWithSaurus(ByVal s As String) _
        As Boolean

        Return s.ToLower().EndsWith("saurus")
    End Function
End Class

' This code example produces the following output:
'
'Compsognathus
'Amargasaurus
'Oviraptor
'Velociraptor
'Deinonychus
'Dilophosaurus
'Gallimimus
'Triceratops
'
'TrueForAll(AddressOf EndsWithSaurus: False
'
'Find(AddressOf EndsWithSaurus): Amargasaurus
'
'FindLast(AddressOf EndsWithSaurus): Dilophosaurus
'
'FindAll(AddressOf EndsWithSaurus):
'Amargasaurus
'Dilophosaurus
'
'2 elements removed by RemoveAll(AddressOf EndsWithSaurus).
'
'List now contains:
'Compsognathus
'Oviraptor
'Velociraptor
'Deinonychus
'Gallimimus
'Triceratops
'
'Exists(AddressOf EndsWithSaurus): False

注釈

Predicate<T> 、渡されたオブジェクトがデリゲートでtrue定義された条件に一致する場合にを返すメソッドのデリゲートです。The Predicate<T> is a delegate to a method that returns true if the object passed to it matches the conditions defined in the delegate. 現在List<T>のの要素は、 Predicate<T>デリゲートに個別に渡され、 List<T>条件に一致する要素がから削除されます。The elements of the current List<T> are individually passed to the Predicate<T> delegate, and the elements that match the conditions are removed from the List<T>.

このメソッドは、線形検索を実行します。したがって、このメソッドは O (n) 演算です。 ** ここでCount、n はです。This method performs a linear search; therefore, this method is an O(n) operation, where n is Count.

適用対象

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