Array.FindIndex Array.FindIndex Array.FindIndex Array.FindIndex Method

定义

搜索与指定谓词定义的条件匹配的元素,然后返回 Array 或其某个部分中第一个匹配项的从零开始的索引。Searches for an element that matches the conditions defined by a specified predicate, and returns the zero-based index of the first occurrence within an Array or a portion of it.

重载

FindIndex<T>(T[], Predicate<T>) FindIndex<T>(T[], Predicate<T>) FindIndex<T>(T[], Predicate<T>) FindIndex<T>(T[], 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 Array 中第一个匹配元素的从零开始的索引。Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the entire Array.

FindIndex<T>(T[], Int32, Predicate<T>) FindIndex<T>(T[], Int32, Predicate<T>) FindIndex<T>(T[], Int32, Predicate<T>) FindIndex<T>(T[], 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 Array 中从指定索引到最后一个元素的元素范围内第一个匹配项的从零开始的索引。Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the Array that extends from the specified index to the last element.

FindIndex<T>(T[], Int32, Int32, Predicate<T>) FindIndex<T>(T[], Int32, Int32, Predicate<T>) FindIndex<T>(T[], Int32, Int32, Predicate<T>) FindIndex<T>(T[], Int32, Int32, Predicate<T>)

搜索与指定谓词所定义的条件相匹配的一个元素,并返回 Array 中从指定的索引开始、包含指定元素个数的元素范围内第一个匹配项的从零开始的索引。Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the Array that starts at the specified index and contains the specified number of elements.

FindIndex<T>(T[], Predicate<T>) FindIndex<T>(T[], Predicate<T>) FindIndex<T>(T[], Predicate<T>) FindIndex<T>(T[], 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 Array 中第一个匹配元素的从零开始的索引。Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the entire Array.

public:
generic <typename T>
 static int FindIndex(cli::array <T> ^ array, Predicate<T> ^ match);
public static int FindIndex<T> (T[] array, Predicate<T> match);
static member FindIndex : 'T[] * Predicate<'T> -> int
Public Shared Function FindIndex(Of T) (array As T(), match As Predicate(Of T)) As Integer

类型参数

T

数组元素的类型。The type of the elements of the array.

参数

array
T[]

要搜索的从零开始的一维 ArrayThe one-dimensional, zero-based Array to search.

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

Predicate<T>,定义要搜索元素的条件。The Predicate<T> that defines the conditions of the element to search for.

返回

如果找到与 match 定义的条件相匹配的第一个元素,则为该元素的从零开始的索引;否则为 -1。The zero-based index of the first occurrence of an element that matches the conditions defined by match, if found; otherwise, -1.

异常

arraynullarray is null.

- 或 --or- matchnullmatch is null.

示例

下面的代码示例演示FindIndex泛型方法的所有三个重载。The following code example demonstrates all three overloads of the FindIndex generic method. 创建一个字符串数组,其中包含8个恐龙名称,其中两个名称(位置1和5)以 "saurus" 结尾。An array of strings is created, containing 8 dinosaur names, two of which (at positions 1 and 5) end with "saurus". 此代码示例还定义了一个名为EndsWithSaurus的搜索谓词方法,该方法接受一个字符串参数,并返回一个布尔值,指示输入字符串是否以 "saurus" 结尾。The code 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".

方法重载从开始处遍历数组,并将每个元素传递EndsWithSaurus给方法。 FindIndex<T>(T[], Predicate<T>)The FindIndex<T>(T[], Predicate<T>) method overload traverses the array from the beginning, passing each element in turn to the EndsWithSaurus method. EndsWithSaurus方法为位置1处的true元素返回时,搜索将停止。The search stops when the EndsWithSaurus method returns true for the element at position 1.

备注

在C#和 Visual Basic 中,无需显式创建Predicate<string>委托(Predicate(Of String)在 Visual Basic 中)。In C# and Visual Basic, it is not necessary to create the Predicate<string> delegate (Predicate(Of String) in Visual Basic) explicitly. 这些语言从上下文推断正确的委托并自动创建它。These languages infer the correct delegate from context and create it automatically.

FindIndex<T>(T[], Int32, Predicate<T>)方法重载用于从位置2开始搜索数组,并继续到数组末尾。The FindIndex<T>(T[], Int32, Predicate<T>) method overload is used to search the array beginning at position 2 and continuing to the end of the array. 它在位置5找到元素。It finds the element at position 5. 最后, FindIndex<T>(T[], Int32, Int32, Predicate<T>)使用方法重载在从位置2开始的三个元素的范围内进行搜索。Finally, the FindIndex<T>(T[], Int32, Int32, Predicate<T>) method overload is used to search the range of three elements beginning at position 2. 它将返回-1,因为该范围中没有以 "saurus" 结尾的恐龙名称。It returns -1 because there are no dinosaur names in that range that end with "saurus".

using namespace System;

// Search predicate returns true if a string ends in "saurus".
bool EndsWithSaurus(String^ s)
{
    if ((s->Length > 5) && 
        (s->Substring(s->Length - 6)->ToLower() == "saurus"))
    {
        return true;
    }
    else
    {
        return false;
    }
};

void main()
{
    array<String^>^ dinosaurs = { "Compsognathus", 
        "Amargasaurus",   "Oviraptor",      "Velociraptor", 
        "Deinonychus",    "Dilophosaurus",  "Gallimimus", 
        "Triceratops" };

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

    Console::WriteLine("\nArray::FindIndex(dinosaurs, EndsWithSaurus): {0}", 
        Array::FindIndex(dinosaurs, gcnew Predicate<String^>(EndsWithSaurus)));

    Console::WriteLine("\nArray::FindIndex(dinosaurs, 2, EndsWithSaurus): {0}",
        Array::FindIndex(dinosaurs, 2, gcnew Predicate<String^>(EndsWithSaurus)));

    Console::WriteLine("\nArray::FindIndex(dinosaurs, 2, 3, EndsWithSaurus): {0}",
        Array::FindIndex(dinosaurs, 2, 3, gcnew Predicate<String^>(EndsWithSaurus)));
}

/* This code example produces the following output:

Compsognathus
Amargasaurus
Oviraptor
Velociraptor
Deinonychus
Dilophosaurus
Gallimimus
Triceratops

Array::FindIndex(dinosaurs, EndsWithSaurus): 1

Array::FindIndex(dinosaurs, 2, EndsWithSaurus): 5

Array::FindIndex(dinosaurs, 2, 3, EndsWithSaurus): -1
 */
using System;

public class Example
{
    public static void Main()
    {
        string[] dinosaurs = { "Compsognathus", 
            "Amargasaurus",   "Oviraptor",      "Velociraptor", 
            "Deinonychus",    "Dilophosaurus",  "Gallimimus", 
            "Triceratops" };

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

        Console.WriteLine(
            "\nArray.FindIndex(dinosaurs, EndsWithSaurus): {0}", 
            Array.FindIndex(dinosaurs, EndsWithSaurus));

        Console.WriteLine(
            "\nArray.FindIndex(dinosaurs, 2, EndsWithSaurus): {0}",
            Array.FindIndex(dinosaurs, 2, EndsWithSaurus));

        Console.WriteLine(
            "\nArray.FindIndex(dinosaurs, 2, 3, EndsWithSaurus): {0}",
            Array.FindIndex(dinosaurs, 2, 3, EndsWithSaurus));
    }

    // Search predicate returns true if a string ends in "saurus".
    private static bool EndsWithSaurus(String s)
    {
        if ((s.Length > 5) && 
            (s.Substring(s.Length - 6).ToLower() == "saurus"))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

/* This code example produces the following output:

Compsognathus
Amargasaurus
Oviraptor
Velociraptor
Deinonychus
Dilophosaurus
Gallimimus
Triceratops

Array.FindIndex(dinosaurs, EndsWithSaurus): 1

Array.FindIndex(dinosaurs, 2, EndsWithSaurus): 5

Array.FindIndex(dinosaurs, 2, 3, EndsWithSaurus): -1
 */
Public Class Example

    Public Shared Sub Main()

        Dim dinosaurs() As String = { "Compsognathus", _
            "Amargasaurus",   "Oviraptor",      "Velociraptor", _
            "Deinonychus",    "Dilophosaurus",  "Gallimimus", _
            "Triceratops" }

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

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

        Console.WriteLine(vbLf & _
            "Array.FindIndex(dinosaurs, 2, AddressOf EndsWithSaurus): {0}", _
            Array.FindIndex(dinosaurs, 2, AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & _
            "Array.FindIndex(dinosaurs, 2, 3, AddressOf EndsWithSaurus): {0}", _
            Array.FindIndex(dinosaurs, 2, 3, AddressOf EndsWithSaurus))

    End Sub

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

        ' AndAlso prevents evaluation of the second Boolean
        ' expression if the string is so short that an error
        ' would occur.
        If (s.Length > 5) AndAlso _
            (s.Substring(s.Length - 6).ToLower() = "saurus") Then
            Return True
        Else
            Return False
        End If
    End Function
End Class

' This code example produces the following output:
'
'Compsognathus
'Amargasaurus
'Oviraptor
'Velociraptor
'Deinonychus
'Dilophosaurus
'Gallimimus
'Triceratops
'
'Array.FindIndex(dinosaurs, AddressOf EndsWithSaurus): 1
'
'Array.FindIndex(dinosaurs, 2, AddressOf EndsWithSaurus): 5
'
'Array.FindIndex(dinosaurs, 2, 3, AddressOf EndsWithSaurus): -1

注解

Array向前搜索从第一个元素开始,到最后一个元素结束。The Array is searched forward starting at the first element and ending at the last element.

是一个方法委托,如果传递给它的对象与委托中定义的条件相匹配,则它将返回truePredicate<T>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. 的元素array分别传递Predicate<T>到。The elements of array are individually passed to the Predicate<T>.

此方法为 On()运算,其中nLengtharrayThis method is an O(n) operation, where n is the Length of array.

另请参阅

FindIndex<T>(T[], Int32, Predicate<T>) FindIndex<T>(T[], Int32, Predicate<T>) FindIndex<T>(T[], Int32, Predicate<T>) FindIndex<T>(T[], 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 Array 中从指定索引到最后一个元素的元素范围内第一个匹配项的从零开始的索引。Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the Array that extends from the specified index to the last element.

public:
generic <typename T>
 static int FindIndex(cli::array <T> ^ array, int startIndex, Predicate<T> ^ match);
public static int FindIndex<T> (T[] array, int startIndex, Predicate<T> match);
static member FindIndex : 'T[] * int * Predicate<'T> -> int
Public Shared Function FindIndex(Of T) (array As T(), startIndex As Integer, match As Predicate(Of T)) As Integer

类型参数

T

数组元素的类型。The type of the elements of the array.

参数

array
T[]

要搜索的从零开始的一维 ArrayThe one-dimensional, zero-based Array to search.

startIndex
Int32 Int32 Int32 Int32

从零开始的搜索的起始索引。The zero-based starting index of the search.

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

Predicate<T>,定义要搜索元素的条件。The Predicate<T> that defines the conditions of the element to search for.

返回

如果找到与 match 定义的条件相匹配的第一个元素,则为该元素的从零开始的索引;否则为 -1。The zero-based index of the first occurrence of an element that matches the conditions defined by match, if found; otherwise, -1.

异常

arraynullarray is null.

- 或 --or- matchnullmatch is null.

startIndex 超出了 array 的有效索引范围。startIndex is outside the range of valid indexes for array.

示例

下面的代码示例演示FindIndex泛型方法的所有三个重载。The following code example demonstrates all three overloads of the FindIndex generic method. 创建一个字符串数组,其中包含8个恐龙名称,其中两个名称(位置1和5)以 "saurus" 结尾。An array of strings is created, containing 8 dinosaur names, two of which (at positions 1 and 5) end with "saurus". 此代码示例还定义了一个名为EndsWithSaurus的搜索谓词方法,该方法接受一个字符串参数,并返回一个布尔值,指示输入字符串是否以 "saurus" 结尾。The code 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".

方法重载从开始处遍历数组,并将每个元素传递EndsWithSaurus给方法。 FindIndex<T>(T[], Predicate<T>)The FindIndex<T>(T[], Predicate<T>) method overload traverses the array from the beginning, passing each element in turn to the EndsWithSaurus method. EndsWithSaurus方法为位置1处的true元素返回时,搜索将停止。The search stops when the EndsWithSaurus method returns true for the element at position 1.

备注

在C#和 Visual Basic 中,无需显式创建Predicate<string>委托(Predicate(Of String)在 Visual Basic 中)。In C# and Visual Basic, it is not necessary to create the Predicate<string> delegate (Predicate(Of String) in Visual Basic) explicitly. 这些语言从上下文推断正确的委托并自动创建它。These languages infer the correct delegate from context and create it automatically.

FindIndex<T>(T[], Int32, Predicate<T>)方法重载用于从位置2开始搜索数组,并继续到数组末尾。The FindIndex<T>(T[], Int32, Predicate<T>) method overload is used to search the array beginning at position 2 and continuing to the end of the array. 它在位置5找到元素。It finds the element at position 5. 最后, FindIndex<T>(T[], Int32, Int32, Predicate<T>)使用方法重载在从位置2开始的三个元素的范围内进行搜索。Finally, the FindIndex<T>(T[], Int32, Int32, Predicate<T>) method overload is used to search the range of three elements beginning at position 2. 它将返回-1,因为该范围中没有以 "saurus" 结尾的恐龙名称。It returns -1 because there are no dinosaur names in that range that end with "saurus".

using namespace System;

// Search predicate returns true if a string ends in "saurus".
bool EndsWithSaurus(String^ s)
{
    if ((s->Length > 5) && 
        (s->Substring(s->Length - 6)->ToLower() == "saurus"))
    {
        return true;
    }
    else
    {
        return false;
    }
};

void main()
{
    array<String^>^ dinosaurs = { "Compsognathus", 
        "Amargasaurus",   "Oviraptor",      "Velociraptor", 
        "Deinonychus",    "Dilophosaurus",  "Gallimimus", 
        "Triceratops" };

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

    Console::WriteLine("\nArray::FindIndex(dinosaurs, EndsWithSaurus): {0}", 
        Array::FindIndex(dinosaurs, gcnew Predicate<String^>(EndsWithSaurus)));

    Console::WriteLine("\nArray::FindIndex(dinosaurs, 2, EndsWithSaurus): {0}",
        Array::FindIndex(dinosaurs, 2, gcnew Predicate<String^>(EndsWithSaurus)));

    Console::WriteLine("\nArray::FindIndex(dinosaurs, 2, 3, EndsWithSaurus): {0}",
        Array::FindIndex(dinosaurs, 2, 3, gcnew Predicate<String^>(EndsWithSaurus)));
}

/* This code example produces the following output:

Compsognathus
Amargasaurus
Oviraptor
Velociraptor
Deinonychus
Dilophosaurus
Gallimimus
Triceratops

Array::FindIndex(dinosaurs, EndsWithSaurus): 1

Array::FindIndex(dinosaurs, 2, EndsWithSaurus): 5

Array::FindIndex(dinosaurs, 2, 3, EndsWithSaurus): -1
 */
using System;

public class Example
{
    public static void Main()
    {
        string[] dinosaurs = { "Compsognathus", 
            "Amargasaurus",   "Oviraptor",      "Velociraptor", 
            "Deinonychus",    "Dilophosaurus",  "Gallimimus", 
            "Triceratops" };

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

        Console.WriteLine(
            "\nArray.FindIndex(dinosaurs, EndsWithSaurus): {0}", 
            Array.FindIndex(dinosaurs, EndsWithSaurus));

        Console.WriteLine(
            "\nArray.FindIndex(dinosaurs, 2, EndsWithSaurus): {0}",
            Array.FindIndex(dinosaurs, 2, EndsWithSaurus));

        Console.WriteLine(
            "\nArray.FindIndex(dinosaurs, 2, 3, EndsWithSaurus): {0}",
            Array.FindIndex(dinosaurs, 2, 3, EndsWithSaurus));
    }

    // Search predicate returns true if a string ends in "saurus".
    private static bool EndsWithSaurus(String s)
    {
        if ((s.Length > 5) && 
            (s.Substring(s.Length - 6).ToLower() == "saurus"))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

/* This code example produces the following output:

Compsognathus
Amargasaurus
Oviraptor
Velociraptor
Deinonychus
Dilophosaurus
Gallimimus
Triceratops

Array.FindIndex(dinosaurs, EndsWithSaurus): 1

Array.FindIndex(dinosaurs, 2, EndsWithSaurus): 5

Array.FindIndex(dinosaurs, 2, 3, EndsWithSaurus): -1
 */
Public Class Example

    Public Shared Sub Main()

        Dim dinosaurs() As String = { "Compsognathus", _
            "Amargasaurus",   "Oviraptor",      "Velociraptor", _
            "Deinonychus",    "Dilophosaurus",  "Gallimimus", _
            "Triceratops" }

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

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

        Console.WriteLine(vbLf & _
            "Array.FindIndex(dinosaurs, 2, AddressOf EndsWithSaurus): {0}", _
            Array.FindIndex(dinosaurs, 2, AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & _
            "Array.FindIndex(dinosaurs, 2, 3, AddressOf EndsWithSaurus): {0}", _
            Array.FindIndex(dinosaurs, 2, 3, AddressOf EndsWithSaurus))

    End Sub

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

        ' AndAlso prevents evaluation of the second Boolean
        ' expression if the string is so short that an error
        ' would occur.
        If (s.Length > 5) AndAlso _
            (s.Substring(s.Length - 6).ToLower() = "saurus") Then
            Return True
        Else
            Return False
        End If
    End Function
End Class

' This code example produces the following output:
'
'Compsognathus
'Amargasaurus
'Oviraptor
'Velociraptor
'Deinonychus
'Dilophosaurus
'Gallimimus
'Triceratops
'
'Array.FindIndex(dinosaurs, AddressOf EndsWithSaurus): 1
'
'Array.FindIndex(dinosaurs, 2, AddressOf EndsWithSaurus): 5
'
'Array.FindIndex(dinosaurs, 2, 3, AddressOf EndsWithSaurus): -1

注解

将从最后一个元素开始向前搜索并结束。startIndex ArrayThe Array is searched forward starting at startIndex and ending at the last element.

是一个方法委托,如果传递给它的对象与委托中定义的条件相匹配,则它将返回truePredicate<T>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. 的元素array分别传递Predicate<T>到。The elements of array are individually passed to the Predicate<T>.

此方法为 On()运算,其中narraystartIndex到末尾的元素数。This method is an O(n) operation, where n is the number of elements from startIndex to the end of array.

另请参阅

FindIndex<T>(T[], Int32, Int32, Predicate<T>) FindIndex<T>(T[], Int32, Int32, Predicate<T>) FindIndex<T>(T[], Int32, Int32, Predicate<T>) FindIndex<T>(T[], Int32, Int32, Predicate<T>)

搜索与指定谓词所定义的条件相匹配的一个元素,并返回 Array 中从指定的索引开始、包含指定元素个数的元素范围内第一个匹配项的从零开始的索引。Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the Array that starts at the specified index and contains the specified number of elements.

public:
generic <typename T>
 static int FindIndex(cli::array <T> ^ array, int startIndex, int count, Predicate<T> ^ match);
public static int FindIndex<T> (T[] array, int startIndex, int count, Predicate<T> match);
static member FindIndex : 'T[] * int * int * Predicate<'T> -> int
Public Shared Function FindIndex(Of T) (array As T(), startIndex As Integer, count As Integer, match As Predicate(Of T)) As Integer

类型参数

T

数组元素的类型。The type of the elements of the array.

参数

array
T[]

要搜索的从零开始的一维 ArrayThe one-dimensional, zero-based Array to search.

startIndex
Int32 Int32 Int32 Int32

从零开始的搜索的起始索引。The zero-based starting index of the search.

count
Int32 Int32 Int32 Int32

要搜索的部分中的元素数。The number of elements in the section to search.

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

Predicate<T>,定义要搜索元素的条件。The Predicate<T> that defines the conditions of the element to search for.

返回

如果找到与 match 定义的条件相匹配的第一个元素,则为该元素的从零开始的索引;否则为 -1。The zero-based index of the first occurrence of an element that matches the conditions defined by match, if found; otherwise, -1.

异常

arraynullarray is null.

- 或 --or- matchnullmatch is null.

startIndex 超出了 array 的有效索引范围。startIndex is outside the range of valid indexes for array.

-or- count 小于零。count is less than zero.

-or- startIndexcount 未在 array 中指定有效部分。startIndex and count do not specify a valid section in array.

示例

下面的代码示例演示FindIndex泛型方法的所有三个重载。The following code example demonstrates all three overloads of the FindIndex generic method. 创建一个字符串数组,其中包含8个恐龙名称,其中两个名称(位置1和5)以 "saurus" 结尾。An array of strings is created, containing 8 dinosaur names, two of which (at positions 1 and 5) end with "saurus". 此代码示例还定义了一个名为EndsWithSaurus的搜索谓词方法,该方法接受一个字符串参数,并返回一个布尔值,指示输入字符串是否以 "saurus" 结尾。The code 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".

方法重载从开始处遍历数组,并将每个元素传递EndsWithSaurus给方法。 FindIndex<T>(T[], Predicate<T>)The FindIndex<T>(T[], Predicate<T>) method overload traverses the array from the beginning, passing each element in turn to the EndsWithSaurus method. EndsWithSaurus方法为位置1处的true元素返回时,搜索将停止。The search stops when the EndsWithSaurus method returns true for the element at position 1.

备注

在C#和 Visual Basic 中,无需显式创建Predicate<string>委托(Predicate(Of String)在 Visual Basic 中)。In C# and Visual Basic, it is not necessary to create the Predicate<string> delegate (Predicate(Of String) in Visual Basic) explicitly. 这些语言从上下文推断正确的委托并自动创建它。These languages infer the correct delegate from context and create it automatically.

FindIndex<T>(T[], Int32, Predicate<T>)方法重载用于从位置2开始搜索数组,并继续到数组末尾。The FindIndex<T>(T[], Int32, Predicate<T>) method overload is used to search the array beginning at position 2 and continuing to the end of the array. 它在位置5找到元素。It finds the element at position 5. 最后, FindIndex<T>(T[], Int32, Int32, Predicate<T>)使用方法重载在从位置2开始的三个元素的范围内进行搜索。Finally, the FindIndex<T>(T[], Int32, Int32, Predicate<T>) method overload is used to search the range of three elements beginning at position 2. 它将返回-1,因为该范围中没有以 "saurus" 结尾的恐龙名称。It returns -1 because there are no dinosaur names in that range that end with "saurus".

using namespace System;

// Search predicate returns true if a string ends in "saurus".
bool EndsWithSaurus(String^ s)
{
    if ((s->Length > 5) && 
        (s->Substring(s->Length - 6)->ToLower() == "saurus"))
    {
        return true;
    }
    else
    {
        return false;
    }
};

void main()
{
    array<String^>^ dinosaurs = { "Compsognathus", 
        "Amargasaurus",   "Oviraptor",      "Velociraptor", 
        "Deinonychus",    "Dilophosaurus",  "Gallimimus", 
        "Triceratops" };

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

    Console::WriteLine("\nArray::FindIndex(dinosaurs, EndsWithSaurus): {0}", 
        Array::FindIndex(dinosaurs, gcnew Predicate<String^>(EndsWithSaurus)));

    Console::WriteLine("\nArray::FindIndex(dinosaurs, 2, EndsWithSaurus): {0}",
        Array::FindIndex(dinosaurs, 2, gcnew Predicate<String^>(EndsWithSaurus)));

    Console::WriteLine("\nArray::FindIndex(dinosaurs, 2, 3, EndsWithSaurus): {0}",
        Array::FindIndex(dinosaurs, 2, 3, gcnew Predicate<String^>(EndsWithSaurus)));
}

/* This code example produces the following output:

Compsognathus
Amargasaurus
Oviraptor
Velociraptor
Deinonychus
Dilophosaurus
Gallimimus
Triceratops

Array::FindIndex(dinosaurs, EndsWithSaurus): 1

Array::FindIndex(dinosaurs, 2, EndsWithSaurus): 5

Array::FindIndex(dinosaurs, 2, 3, EndsWithSaurus): -1
 */
using System;

public class Example
{
    public static void Main()
    {
        string[] dinosaurs = { "Compsognathus", 
            "Amargasaurus",   "Oviraptor",      "Velociraptor", 
            "Deinonychus",    "Dilophosaurus",  "Gallimimus", 
            "Triceratops" };

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

        Console.WriteLine(
            "\nArray.FindIndex(dinosaurs, EndsWithSaurus): {0}", 
            Array.FindIndex(dinosaurs, EndsWithSaurus));

        Console.WriteLine(
            "\nArray.FindIndex(dinosaurs, 2, EndsWithSaurus): {0}",
            Array.FindIndex(dinosaurs, 2, EndsWithSaurus));

        Console.WriteLine(
            "\nArray.FindIndex(dinosaurs, 2, 3, EndsWithSaurus): {0}",
            Array.FindIndex(dinosaurs, 2, 3, EndsWithSaurus));
    }

    // Search predicate returns true if a string ends in "saurus".
    private static bool EndsWithSaurus(String s)
    {
        if ((s.Length > 5) && 
            (s.Substring(s.Length - 6).ToLower() == "saurus"))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

/* This code example produces the following output:

Compsognathus
Amargasaurus
Oviraptor
Velociraptor
Deinonychus
Dilophosaurus
Gallimimus
Triceratops

Array.FindIndex(dinosaurs, EndsWithSaurus): 1

Array.FindIndex(dinosaurs, 2, EndsWithSaurus): 5

Array.FindIndex(dinosaurs, 2, 3, EndsWithSaurus): -1
 */
Public Class Example

    Public Shared Sub Main()

        Dim dinosaurs() As String = { "Compsognathus", _
            "Amargasaurus",   "Oviraptor",      "Velociraptor", _
            "Deinonychus",    "Dilophosaurus",  "Gallimimus", _
            "Triceratops" }

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

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

        Console.WriteLine(vbLf & _
            "Array.FindIndex(dinosaurs, 2, AddressOf EndsWithSaurus): {0}", _
            Array.FindIndex(dinosaurs, 2, AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & _
            "Array.FindIndex(dinosaurs, 2, 3, AddressOf EndsWithSaurus): {0}", _
            Array.FindIndex(dinosaurs, 2, 3, AddressOf EndsWithSaurus))

    End Sub

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

        ' AndAlso prevents evaluation of the second Boolean
        ' expression if the string is so short that an error
        ' would occur.
        If (s.Length > 5) AndAlso _
            (s.Substring(s.Length - 6).ToLower() = "saurus") Then
            Return True
        Else
            Return False
        End If
    End Function
End Class

' This code example produces the following output:
'
'Compsognathus
'Amargasaurus
'Oviraptor
'Velociraptor
'Deinonychus
'Dilophosaurus
'Gallimimus
'Triceratops
'
'Array.FindIndex(dinosaurs, AddressOf EndsWithSaurus): 1
'
'Array.FindIndex(dinosaurs, 2, AddressOf EndsWithSaurus): 5
'
'Array.FindIndex(dinosaurs, 2, 3, AddressOf EndsWithSaurus): -1

注解

startIndex startIndex count如果Array 大于0,则从开始向前搜索,并在plus减1处结束。countThe Array is searched forward starting at startIndex and ending at startIndex plus count minus 1, if count is greater than 0.

是一个方法委托,如果传递给它的对象与委托中定义的条件相匹配,则它将返回truePredicate<T>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. 的元素array分别传递Predicate<T>到。The elements of array are individually passed to the Predicate<T>.

此方法是 O (n)运算,其中ncountThis method is an O(n) operation, where n is count.

另请参阅

适用于