List<T>.FindLastIndex 方法

参考

定义

命名空间:: System.Collections.Generic

程序集:: System.Collections.dll

程序集:: mscorlib.dll

程序集:: netstandard.dll

重要

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搜索与指定谓词所定义的条件相匹配的元素，返回 List<T> 或它的一部分中最后一个匹配项的从零开始的索引。

重载

FindLastIndex(Predicate<T>)	搜索与指定谓词所定义的条件相匹配的元素，并返回整个 List<T> 中最后一个匹配元素的从零开始的索引。
FindLastIndex(Int32, Predicate<T>)	搜索与由指定谓词定义的条件相匹配的元素，并返回 List<T> 中从第一个元素到指定索引的元素范围内最后一个匹配项的从零开始的索引。
FindLastIndex(Int32, Int32, Predicate<T>)	搜索与指定谓词所定义的条件相匹配的元素，并返回 List<T> 中包含指定元素个数、到指定索引结束的元素范围内最后一个匹配项的从零开始的索引。

FindLastIndex(Predicate<T>)

Source:: List.cs

Source:: List.cs

Source:: List.cs

搜索与指定谓词所定义的条件相匹配的元素，并返回整个 List<T> 中最后一个匹配元素的从零开始的索引。

public:
 int FindLastIndex(Predicate<T> ^ match);

public int FindLastIndex (Predicate<T> match);

member this.FindLastIndex : Predicate<'T> -> int

Public Function FindLastIndex (match As Predicate(Of T)) As Integer

参数

match: Predicate<T>

Predicate<T> 委托，用于定义要搜索的元素的条件。

Int32

如果找到与 match 定义的条件相匹配的最后一个元素，则为该元素的从零开始的索引；否则为 -1。

例外

ArgumentNullException

match 为 null。

示例

以下示例演示类的查找方法 List<T> 。类的示例包含类的对象，使用示例 XML 文件中的数据：LINQ to XML) (书籍。BookbookList<T> FillList示例中的方法使用 LINQ to XML 将 XML 中的值解析为对象的属性值book。

下表描述了为 find 方法提供的示例。

方法	示例
Find(Predicate<T>)	使用 `IDToFind` 谓词委托按 ID 查找书籍。 C# 示例使用匿名委托。
FindAll(Predicate<T>)	使用`FindComputer`谓词委托查找属性为“Computer”的所有书籍`Genre`。
FindLast(Predicate<T>)	使用 `PubBefore2001` 谓词委托查找集合中发布日期早于 2001 的最后一本书。 C# 示例使用匿名委托。
FindIndex(Predicate<T>)	使用谓词委托查找第一本计算机书籍的 `FindComputer` 索引。
FindLastIndex(Predicate<T>)	使用谓词委托查找最后一个计算机书籍的 `FindComputer` 索引。
FindIndex(Int32, Int32, Predicate<T>)	使用谓词委托查找集合后半部分中第一本计算机书籍的 `FindComputer` 索引。
FindLastIndex(Int32, Int32, Predicate<T>)	使用谓词委托查找集合后半部分中最后一本计算机书籍的 `FindComputer` 索引。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Xml.Linq;

namespace Find
{
    class Program
    {
        private static string IDtoFind = "bk109";

        private static List<Book> Books = new List<Book>();
        public static void Main(string[] args)
        {
            FillList();

            // Find a book by its ID.
            Book result = Books.Find(
            delegate(Book bk)
            {
                return bk.ID == IDtoFind;
            }
            );
            if (result != null)
            {
                DisplayResult(result, "Find by ID: " + IDtoFind);
            }
            else
            {
                Console.WriteLine("\nNot found: {0}", IDtoFind);
            }

            // Find last book in collection published before 2001.
            result = Books.FindLast(
            delegate(Book bk)
            {
                DateTime year2001 = new DateTime(2001,01,01);
                return bk.Publish_date < year2001;
            });
            if (result != null)
            {
                DisplayResult(result, "Last book in collection published before 2001:");
            }
            else
            {
                Console.WriteLine("\nNot found: {0}", IDtoFind);
            }

            // Find all computer books.
            List<Book> results = Books.FindAll(FindComputer);
            if (results.Count != 0)
            {
                DisplayResults(results, "All computer:");
            }
            else
            {
                Console.WriteLine("\nNo books found.");
            }

            // Find all books under $10.00.
            results = Books.FindAll(
            delegate(Book bk)
            {
                return bk.Price < 10.00;
            }
            );
            if (results.Count != 0)
            {
                DisplayResults(results, "Books under $10:");
            }
            else
            {
                Console.WriteLine("\nNo books found.");
            }

            // Find index values.
            Console.WriteLine();
            int ndx = Books.FindIndex(FindComputer);
            Console.WriteLine("Index of first computer book: {0}", ndx);
            ndx = Books.FindLastIndex(FindComputer);
            Console.WriteLine("Index of last computer book: {0}", ndx);

            int mid = Books.Count / 2;
            ndx = Books.FindIndex(mid, mid, FindComputer);
            Console.WriteLine("Index of first computer book in the second half of the collection: {0}", ndx);

            ndx = Books.FindLastIndex(Books.Count - 1, mid, FindComputer);
            Console.WriteLine("Index of last computer book in the second half of the collection: {0}", ndx);
        }

        // Populates the list with sample data.
        private static void FillList()
        {

            // Create XML elements from a source file.
            XElement xTree = XElement.Load(@"c:\temp\books.xml");

            // Create an enumerable collection of the elements.
            IEnumerable<XElement> elements = xTree.Elements();

            // Evaluate each element and set set values in the book object.
            foreach (XElement el in elements)
            {
                Book book = new Book();
                book.ID = el.Attribute("id").Value;
                IEnumerable<XElement> props = el.Elements();
                foreach (XElement p in props)
                {

                    if (p.Name.ToString().ToLower() == "author")
                    {
                        book.Author = p.Value;
                    }
                    else if (p.Name.ToString().ToLower() == "title")
                    {
                        book.Title = p.Value;
                    }
                    else if (p.Name.ToString().ToLower() == "genre")
                    {
                        book.Genre = p.Value;
                    }
                    else if (p.Name.ToString().ToLower() == "price")
                    {
                        book.Price = Convert.ToDouble(p.Value);
                    }
                    else if (p.Name.ToString().ToLower() == "publish_date")
                    {
                        book.Publish_date = Convert.ToDateTime(p.Value);
                    }
                    else if (p.Name.ToString().ToLower() == "description")
                    {
                        book.Description = p.Value;
                    }
                }

                Books.Add(book);
            }

            DisplayResults(Books, "All books:");
        }

        // Explicit predicate delegate.
        private static bool FindComputer(Book bk)
        {

            if (bk.Genre == "Computer")
            {
                return true;
            }
        else
            {
                return false;
            }
        }

        private static void DisplayResult(Book result, string title)
        {
            Console.WriteLine();
            Console.WriteLine(title);
            Console.WriteLine("\n{0}\t{1}\t{2}\t{3}\t{4}\t{5}", result.ID,
                result.Author, result.Title, result.Genre, result.Price,
                result.Publish_date.ToShortDateString());
            Console.WriteLine();
        }

        private static void DisplayResults(List<Book> results, string title)
        {
            Console.WriteLine();
            Console.WriteLine(title);
            foreach (Book b in results)
            {

                Console.Write("\n{0}\t{1}\t{2}\t{3}\t{4}\t{5}", b.ID,
                    b.Author, b.Title, b.Genre, b.Price,
                    b.Publish_date.ToShortDateString());
            }
            Console.WriteLine();
        }
    }

    public class Book
    {
        public string ID { get; set; }
        public string Author { get; set; }
        public string Title { get; set; }
        public string Genre { get; set; }
        public double Price { get; set; }
        public DateTime Publish_date { get; set; }
        public string Description { get; set; }
    }
}

Imports System.Collections.Generic
Imports System.Linq
Imports System.Xml.Linq
Module Module1

    Private IDToFind As String = "bk109"

    Public Books As New List(Of Book)


    Sub Main()

        FillList()

        ' Find a book by its ID.
        Dim result As Book = Books.Find(AddressOf FindID)
        If result IsNot Nothing Then
            DisplayResult(result, "Find by ID: " & IDToFind)
        Else

            Console.WriteLine(vbCrLf & "Not found: " & IDToFind)
        End If
        Console.WriteLine()

        ' Find last book in collection that has a publish date before 2001.
        result = Books.FindLast(AddressOf PubBefore2001)
        If result IsNot Nothing Then
            DisplayResult(result, "Last book in collection published before 2001:")
        Else
            Console.WriteLine(vbCrLf & "Not found: " & IDToFind)
        End If
        Console.WriteLine()

        ' Find all computer books.
        Dim results As List(Of Book) = Books.FindAll(AddressOf FindComputer)
        If results.Count <> 0 Then
            DisplayResults(results, "All computer books:")
        Else
            Console.WriteLine(vbCrLf & "No books found.")
        End If
        Console.WriteLine()


        ' Find all books under $10.00.
        results = Books.FindAll(AddressOf FindUnderTen)
        If results.Count <> 0 Then
            DisplayResults(results, "Books under $10:")
        Else
            Console.WriteLine(vbCrLf & "No books found.")
        End If
        Console.WriteLine()

        ' Find index values.
        Console.WriteLine()
        Dim ndx As Integer = Books.FindIndex(AddressOf FindComputer)
        Console.WriteLine("Index of first computer book: " & ndx)
        ndx = Books.FindLastIndex(AddressOf FindComputer)
        Console.WriteLine("Index of last computer book: " & ndx)

        Dim mid As Integer = Books.Count / 2
        ndx = Books.FindIndex(mid, mid, AddressOf FindComputer)
        Console.WriteLine("Index of first computer book in the second half of the collection: " & ndx)



        ndx = Books.FindLastIndex(Books.Count - 1, mid, AddressOf FindComputer)
        Console.WriteLine("Index of last computer book in the second half of the collection: " & ndx)


    End Sub



    Private Sub FillList()

        ' Create XML elements from a source file.
        Dim xTree As XElement = XElement.Load("c:\temp\books.xml")

        ' Create an enumerable collection of the elements.
        Dim elements As IEnumerable(Of XElement) = xTree.Elements

        ' Evaluate each element and set values in the book object.
        For Each el As XElement In elements
            Dim Book As New Book()
            Book.ID = el.Attribute("id").Value
            Dim props As IEnumerable(Of XElement) = el.Elements
            For Each p As XElement In props
                If p.Name.ToString.ToLower = "author" Then
                    Book.Author = p.Value
                End If
                If p.Name.ToString.ToLower = "title" Then
                    Book.Title = p.Value
                End If
                If p.Name.ToString.ToLower = "genre" Then
                    Book.Genre = p.Value
                End If
                If p.Name.ToString.ToLower = "price" Then
                    Book.Price = Convert.ToDouble(p.Value)
                End If
                If p.Name.ToString.ToLower = "publish_date" Then
                    Book.Publish_date = Convert.ToDateTime(p.Value)
                End If
                If p.Name.ToString.ToLower = "description" Then
                    Book.Description = p.Value
                End If
            Next
            Books.Add(Book)
        Next

        DisplayResults(Books, "All books:")
        Console.WriteLine()

    End Sub

    ' Predicate delegates for
    ' Find and FindAll methods.
    Private Function FindID(ByVal bk As Book) As Boolean
        If bk.ID = IDToFind Then
            Return True
        Else
            Return False
        End If
    End Function
    Private Function FindComputer(ByVal bk As Book) As Boolean
        If bk.Genre = "Computer" Then
            Return True
        Else
            Return False
        End If
    End Function
    Private Function FindUnderTen(ByVal bk As Book) As Boolean
        Dim tendollars As Double = 10.0
        If bk.Price < tendollars Then
            Return True
        Else
            Return False
        End If
    End Function
    Private Function PubBefore2001(ByVal bk As Book) As Boolean
        Dim year2001 As DateTime = New DateTime(2001, 1, 1)
        Return bk.Publish_date < year2001
    End Function
    Private Sub DisplayResult(ByVal result As Book, ByVal title As String)
        Console.WriteLine()
        Console.WriteLine(title)
        Console.WriteLine(vbLf & result.ID & vbTab & result.Author & _
                          vbTab & result.Title & vbTab & result.Genre & _
                          vbTab & result.Publish_date & vbTab & result.Price)
        Console.WriteLine()
    End Sub
    Private Sub DisplayResults(ByVal results As List(Of Book), ByVal title As String)
        Console.WriteLine()
        Console.WriteLine(title)
        For Each b As Book In results
            Console.Write(vbLf & b.ID & vbTab & b.Author & _
                              vbTab & b.Title & vbTab & b.Genre & _
                              vbTab & b.Publish_date & vbTab & b.Price)
        Next
        Console.WriteLine()
    End Sub

    Public Class Book
        Public ID As String
        Public Author As String
        Public Title As String
        Public Genre As String
        Public Price As Double
        Public Publish_date As DateTime
        Public Description As String
    End Class


End Module

注解

从 List<T> 最后一个元素开始，在第一个元素结束，向后搜索。

Predicate<T>是方法的true委托，如果传递给该方法的对象与委托中定义的条件匹配，则返回。当前 List<T> 的元素单独传递给 Predicate<T> 委托。

此方法执行线性搜索;因此，此方法是 O (n) 操作，其中 n 为 Count。

另请参阅

适用于

FindLastIndex(Int32, Predicate<T>)

Source:: List.cs

Source:: List.cs

Source:: List.cs

搜索与由指定谓词定义的条件相匹配的元素，并返回 List<T> 中从第一个元素到指定索引的元素范围内最后一个匹配项的从零开始的索引。

public:
 int FindLastIndex(int startIndex, Predicate<T> ^ match);

public int FindLastIndex (int startIndex, Predicate<T> match);

member this.FindLastIndex : int * Predicate<'T> -> int

Public Function FindLastIndex (startIndex As Integer, match As Predicate(Of T)) As Integer

参数

startIndex: Int32

向后搜索的从零开始的起始索引。

match: Predicate<T>

Predicate<T> 委托，用于定义要搜索的元素的条件。

Int32

如果找到与 match 定义的条件相匹配的最后一个元素，则为该元素的从零开始的索引；否则为 -1。

例外

ArgumentNullException

match 为 null。

ArgumentOutOfRangeException

startIndex 超出了 List<T> 的有效索引范围。

注解

List<T>从第一个元素开始startIndex向后搜索，并在第一个元素处结束。

Predicate<T>是方法的true委托，如果传递给该方法的对象与委托中定义的条件匹配，则返回。当前 List<T> 的元素单独传递给 Predicate<T> 委托。

此方法执行线性搜索;因此，此方法是 O (n) 操作，其中 n 是从开头到 startIndex的List<T>元素数。

另请参阅

适用于

FindLastIndex(Int32, Int32, Predicate<T>)

Source:: List.cs

Source:: List.cs

Source:: List.cs

搜索与指定谓词所定义的条件相匹配的元素，并返回 List<T> 中包含指定元素个数、到指定索引结束的元素范围内最后一个匹配项的从零开始的索引。

public:
 int FindLastIndex(int startIndex, int count, Predicate<T> ^ match);

public int FindLastIndex (int startIndex, int count, Predicate<T> match);

member this.FindLastIndex : int * int * Predicate<'T> -> int

Public Function FindLastIndex (startIndex As Integer, count As Integer, match As Predicate(Of T)) As Integer

参数

startIndex: Int32

向后搜索的从零开始的起始索引。

count: Int32

要搜索的部分中的元素数。

match: Predicate<T>

Predicate<T> 委托，用于定义要搜索的元素的条件。

Int32

如果找到与 match 定义的条件相匹配的最后一个元素，则为该元素的从零开始的索引；否则为 -1。

例外

ArgumentNullException

match 为 null。

ArgumentOutOfRangeException

startIndex 超出了 List<T> 的有效索引范围。

- 或 -

count 小于 0。

- 或 -

startIndex 和 count 未在 List<T> 中指定有效部分。

示例

下表描述了为 find 方法提供的示例。

方法	示例
Find(Predicate<T>)	使用 `IDToFind` 谓词委托按 ID 查找书籍。 C# 示例使用匿名委托。
FindAll(Predicate<T>)	使用`FindComputer`谓词委托查找属性为“Computer”的所有书籍`Genre`。
FindLast(Predicate<T>)	使用 `PubBefore2001` 谓词委托查找集合中发布日期早于 2001 的最后一本书。 C# 示例使用匿名委托。
FindIndex(Predicate<T>)	使用谓词委托查找第一本计算机书籍的 `FindComputer` 索引。
FindLastIndex(Predicate<T>)	使用谓词委托查找最后一个计算机书籍的 `FindComputer` 索引。
FindIndex(Int32, Int32, Predicate<T>)	使用谓词委托查找集合后半部分中第一本计算机书籍的 `FindComputer` 索引。
FindLastIndex(Int32, Int32, Predicate<T>)	使用谓词委托查找集合后半部分中最后一本计算机书籍的 `FindComputer` 索引。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Xml.Linq;

namespace Find
{
    class Program
    {
        private static string IDtoFind = "bk109";

        private static List<Book> Books = new List<Book>();
        public static void Main(string[] args)
        {
            FillList();

            // Find a book by its ID.
            Book result = Books.Find(
            delegate(Book bk)
            {
                return bk.ID == IDtoFind;
            }
            );
            if (result != null)
            {
                DisplayResult(result, "Find by ID: " + IDtoFind);
            }
            else
            {
                Console.WriteLine("\nNot found: {0}", IDtoFind);
            }

            // Find last book in collection published before 2001.
            result = Books.FindLast(
            delegate(Book bk)
            {
                DateTime year2001 = new DateTime(2001,01,01);
                return bk.Publish_date < year2001;
            });
            if (result != null)
            {
                DisplayResult(result, "Last book in collection published before 2001:");
            }
            else
            {
                Console.WriteLine("\nNot found: {0}", IDtoFind);
            }

            // Find all computer books.
            List<Book> results = Books.FindAll(FindComputer);
            if (results.Count != 0)
            {
                DisplayResults(results, "All computer:");
            }
            else
            {
                Console.WriteLine("\nNo books found.");
            }

            // Find all books under $10.00.
            results = Books.FindAll(
            delegate(Book bk)
            {
                return bk.Price < 10.00;
            }
            );
            if (results.Count != 0)
            {
                DisplayResults(results, "Books under $10:");
            }
            else
            {
                Console.WriteLine("\nNo books found.");
            }

            // Find index values.
            Console.WriteLine();
            int ndx = Books.FindIndex(FindComputer);
            Console.WriteLine("Index of first computer book: {0}", ndx);
            ndx = Books.FindLastIndex(FindComputer);
            Console.WriteLine("Index of last computer book: {0}", ndx);

            int mid = Books.Count / 2;
            ndx = Books.FindIndex(mid, mid, FindComputer);
            Console.WriteLine("Index of first computer book in the second half of the collection: {0}", ndx);

            ndx = Books.FindLastIndex(Books.Count - 1, mid, FindComputer);
            Console.WriteLine("Index of last computer book in the second half of the collection: {0}", ndx);
        }

        // Populates the list with sample data.
        private static void FillList()
        {

            // Create XML elements from a source file.
            XElement xTree = XElement.Load(@"c:\temp\books.xml");

            // Create an enumerable collection of the elements.
            IEnumerable<XElement> elements = xTree.Elements();

            // Evaluate each element and set set values in the book object.
            foreach (XElement el in elements)
            {
                Book book = new Book();
                book.ID = el.Attribute("id").Value;
                IEnumerable<XElement> props = el.Elements();
                foreach (XElement p in props)
                {

                    if (p.Name.ToString().ToLower() == "author")
                    {
                        book.Author = p.Value;
                    }
                    else if (p.Name.ToString().ToLower() == "title")
                    {
                        book.Title = p.Value;
                    }
                    else if (p.Name.ToString().ToLower() == "genre")
                    {
                        book.Genre = p.Value;
                    }
                    else if (p.Name.ToString().ToLower() == "price")
                    {
                        book.Price = Convert.ToDouble(p.Value);
                    }
                    else if (p.Name.ToString().ToLower() == "publish_date")
                    {
                        book.Publish_date = Convert.ToDateTime(p.Value);
                    }
                    else if (p.Name.ToString().ToLower() == "description")
                    {
                        book.Description = p.Value;
                    }
                }

                Books.Add(book);
            }

            DisplayResults(Books, "All books:");
        }

        // Explicit predicate delegate.
        private static bool FindComputer(Book bk)
        {

            if (bk.Genre == "Computer")
            {
                return true;
            }
        else
            {
                return false;
            }
        }

        private static void DisplayResult(Book result, string title)
        {
            Console.WriteLine();
            Console.WriteLine(title);
            Console.WriteLine("\n{0}\t{1}\t{2}\t{3}\t{4}\t{5}", result.ID,
                result.Author, result.Title, result.Genre, result.Price,
                result.Publish_date.ToShortDateString());
            Console.WriteLine();
        }

        private static void DisplayResults(List<Book> results, string title)
        {
            Console.WriteLine();
            Console.WriteLine(title);
            foreach (Book b in results)
            {

                Console.Write("\n{0}\t{1}\t{2}\t{3}\t{4}\t{5}", b.ID,
                    b.Author, b.Title, b.Genre, b.Price,
                    b.Publish_date.ToShortDateString());
            }
            Console.WriteLine();
        }
    }

    public class Book
    {
        public string ID { get; set; }
        public string Author { get; set; }
        public string Title { get; set; }
        public string Genre { get; set; }
        public double Price { get; set; }
        public DateTime Publish_date { get; set; }
        public string Description { get; set; }
    }
}

Imports System.Collections.Generic
Imports System.Linq
Imports System.Xml.Linq
Module Module1

    Private IDToFind As String = "bk109"

    Public Books As New List(Of Book)


    Sub Main()

        FillList()

        ' Find a book by its ID.
        Dim result As Book = Books.Find(AddressOf FindID)
        If result IsNot Nothing Then
            DisplayResult(result, "Find by ID: " & IDToFind)
        Else

            Console.WriteLine(vbCrLf & "Not found: " & IDToFind)
        End If
        Console.WriteLine()

        ' Find last book in collection that has a publish date before 2001.
        result = Books.FindLast(AddressOf PubBefore2001)
        If result IsNot Nothing Then
            DisplayResult(result, "Last book in collection published before 2001:")
        Else
            Console.WriteLine(vbCrLf & "Not found: " & IDToFind)
        End If
        Console.WriteLine()

        ' Find all computer books.
        Dim results As List(Of Book) = Books.FindAll(AddressOf FindComputer)
        If results.Count <> 0 Then
            DisplayResults(results, "All computer books:")
        Else
            Console.WriteLine(vbCrLf & "No books found.")
        End If
        Console.WriteLine()


        ' Find all books under $10.00.
        results = Books.FindAll(AddressOf FindUnderTen)
        If results.Count <> 0 Then
            DisplayResults(results, "Books under $10:")
        Else
            Console.WriteLine(vbCrLf & "No books found.")
        End If
        Console.WriteLine()

        ' Find index values.
        Console.WriteLine()
        Dim ndx As Integer = Books.FindIndex(AddressOf FindComputer)
        Console.WriteLine("Index of first computer book: " & ndx)
        ndx = Books.FindLastIndex(AddressOf FindComputer)
        Console.WriteLine("Index of last computer book: " & ndx)

        Dim mid As Integer = Books.Count / 2
        ndx = Books.FindIndex(mid, mid, AddressOf FindComputer)
        Console.WriteLine("Index of first computer book in the second half of the collection: " & ndx)



        ndx = Books.FindLastIndex(Books.Count - 1, mid, AddressOf FindComputer)
        Console.WriteLine("Index of last computer book in the second half of the collection: " & ndx)


    End Sub



    Private Sub FillList()

        ' Create XML elements from a source file.
        Dim xTree As XElement = XElement.Load("c:\temp\books.xml")

        ' Create an enumerable collection of the elements.
        Dim elements As IEnumerable(Of XElement) = xTree.Elements

        ' Evaluate each element and set values in the book object.
        For Each el As XElement In elements
            Dim Book As New Book()
            Book.ID = el.Attribute("id").Value
            Dim props As IEnumerable(Of XElement) = el.Elements
            For Each p As XElement In props
                If p.Name.ToString.ToLower = "author" Then
                    Book.Author = p.Value
                End If
                If p.Name.ToString.ToLower = "title" Then
                    Book.Title = p.Value
                End If
                If p.Name.ToString.ToLower = "genre" Then
                    Book.Genre = p.Value
                End If
                If p.Name.ToString.ToLower = "price" Then
                    Book.Price = Convert.ToDouble(p.Value)
                End If
                If p.Name.ToString.ToLower = "publish_date" Then
                    Book.Publish_date = Convert.ToDateTime(p.Value)
                End If
                If p.Name.ToString.ToLower = "description" Then
                    Book.Description = p.Value
                End If
            Next
            Books.Add(Book)
        Next

        DisplayResults(Books, "All books:")
        Console.WriteLine()

    End Sub

    ' Predicate delegates for
    ' Find and FindAll methods.
    Private Function FindID(ByVal bk As Book) As Boolean
        If bk.ID = IDToFind Then
            Return True
        Else
            Return False
        End If
    End Function
    Private Function FindComputer(ByVal bk As Book) As Boolean
        If bk.Genre = "Computer" Then
            Return True
        Else
            Return False
        End If
    End Function
    Private Function FindUnderTen(ByVal bk As Book) As Boolean
        Dim tendollars As Double = 10.0
        If bk.Price < tendollars Then
            Return True
        Else
            Return False
        End If
    End Function
    Private Function PubBefore2001(ByVal bk As Book) As Boolean
        Dim year2001 As DateTime = New DateTime(2001, 1, 1)
        Return bk.Publish_date < year2001
    End Function
    Private Sub DisplayResult(ByVal result As Book, ByVal title As String)
        Console.WriteLine()
        Console.WriteLine(title)
        Console.WriteLine(vbLf & result.ID & vbTab & result.Author & _
                          vbTab & result.Title & vbTab & result.Genre & _
                          vbTab & result.Publish_date & vbTab & result.Price)
        Console.WriteLine()
    End Sub
    Private Sub DisplayResults(ByVal results As List(Of Book), ByVal title As String)
        Console.WriteLine()
        Console.WriteLine(title)
        For Each b As Book In results
            Console.Write(vbLf & b.ID & vbTab & b.Author & _
                              vbTab & b.Title & vbTab & b.Genre & _
                              vbTab & b.Publish_date & vbTab & b.Price)
        Next
        Console.WriteLine()
    End Sub

    Public Class Book
        Public ID As String
        Public Author As String
        Public Title As String
        Public Genre As String
        Public Price As Double
        Public Publish_date As DateTime
        Public Description As String
    End Class


End Module

注解

List<T>如果 count 大于 0，则向后搜索，从startIndex减去count加 1 结束startIndex。

Predicate<T>是方法的true委托，如果传递给该方法的对象与委托中定义的条件匹配，则返回。当前 List<T> 的元素单独传递给 Predicate<T> 委托。

此方法执行线性搜索;因此，此方法是 O (n) 操作，其中 n 为 count。

另请参阅

适用于

List<T>.FindLastIndex 方法

定义

重载

FindLastIndex(Predicate<T>)

参数

返回

例外

示例

注解

另请参阅

适用于

FindLastIndex(Int32, Predicate<T>)

参数

返回

例外

注解

另请参阅

适用于

FindLastIndex(Int32, Int32, Predicate<T>)

参数

返回

例外

示例

注解

另请参阅

适用于

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