Action<T1,T2,T3,T4> 代理人

定義

命名空間:: System

組件:: mscorlib.dll, System.Runtime.dll

組件:: netstandard.dll, System.Runtime.dll

組件:: System.Runtime.dll

組件:: System.Core.dll

組件:: mscorlib.dll

組件:: netstandard.dll

來源:: Action.cs

來源:: Action.cs

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

封裝了一個包含四個參數且不回傳值的方法。

generic <typename T1, typename T2, typename T3, typename T4>
public delegate void Action(T1 arg1, T2 arg2, T3 arg3, T4 arg4);

public delegate void Action<in T1,in T2,in T3,in T4>(T1 arg1, T2 arg2, T3 arg3, T4 arg4);

public delegate void Action<in T1,in T2,in T3,in T4>(T1 arg1, T2 arg2, T3 arg3, T4 arg4) where T1 : allows ref struct where T2 : allows ref struct where T3 : allows ref struct where T4 : allows ref struct;

public delegate void Action<T1,T2,T3,T4>(T1 arg1, T2 arg2, T3 arg3, T4 arg4);

type Action<'T1, 'T2, 'T3, 'T4> = delegate of 'T1 * 'T2 * 'T3 * 'T4 -> unit

Public Delegate Sub Action(Of In T1, In T2, In T3, In T4)(arg1 As T1, arg2 As T2, arg3 As T3, arg4 As T4)

Public Delegate Sub Action(Of T1, T2, T3, T4)(arg1 As T1, arg2 As T2, arg3 As T3, arg4 As T4)

類型參數

T1

此代理所封裝的方法第一個參數類型。

這是反變數的型別參數。也就是說，您可以使用您指定的類型，或衍生程度較低的任何類型。如需共變數與反變數的詳細資訊，請參閱泛型中的共變數與反變數。

T2

此代理所封裝的方法第二個參數類型。

T3

此代理所封裝的方法第三參數類型。

T4

此代理所封裝的方法第四參數類型。

參數

arg1: T1

這個代表所封裝的方法的第一個參數。

arg2: T2

這個代表所涵蓋的方法的第二個參數。

arg3: T3

這個代表所涵蓋的方法的第三個參數。

arg4: T4

這個代理所封裝的方法的第四個參數。

備註

你可以用 Action<T1,T2,T3,T4> 代理來傳遞方法作為參數，而不必明確宣告自訂代理。封裝方法必須對應於此代理所定義的方法簽名。這表示封裝方法必須有四個參數，且這些參數皆以值傳遞給它，且不能回傳值。（在 C# 中，方法必須回傳 void。在 F# 中，方法或函式必須回傳單位。在 Visual Basic 中，必須由 Sub...End Sub 結構來定義。它也可以是回傳一個被忽略的值。）通常，這類方法用於執行操作。

備註

若要參考一個有四個參數並回傳值的方法，請改用通用 Func<T1,T2,T3,T4,TResult> 代理。

使用 Action<T1,T2,T3,T4> 代理時，不必明確定義一個以四個參數封裝方法的代理。例如，以下程式碼明確宣告一個名為代理 StringCopy 的代理，並將該方法的參考 CopyStrings 指派給其代理實例。

using System;

delegate void StringCopy(string[] stringArray1,
                         string[] stringArray2,
                         int indexToStart,
                         int numberToCopy);

public class TestDelegate
{
    public static void Main()
    {
        string[] ordinals = ["First", "Second", "Third", "Fourth", "Fifth",
                           "Sixth", "Seventh", "Eighth", "Ninth", "Tenth"];
        string[] copiedOrdinals = new string[ordinals.Length];
        StringCopy copyOperation = CopyStrings;
        copyOperation(ordinals, copiedOrdinals, 3, 5);

        Console.WriteLine();
        foreach (string ordinal in copiedOrdinals)
            Console.WriteLine(string.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
    }

    private static void CopyStrings(string[] source, string[] target,
                                    int startPos, int number)
    {
        if (source.Length != target.Length)
            throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

        for (int ctr = startPos; ctr <= startPos + number - 1; ctr++)
            target[ctr] = source[ctr];
    }
}

open System

type StringCopy = delegate of stringArray1: string [] *
                              stringArray2: string [] *
                              indexToStart: int *
                              numberToCopy: int -> unit

let copyStrings (source: string []) (target: string []) startPos number =
    if source.Length <> target.Length then
        raise (IndexOutOfRangeException "The source and target arrays must have the same number of elements.")

    for i = startPos to startPos + number - 1 do
        target.[i] <- source.[i]

let ordinals =
    [| "First"; "Second"; "Third"; "Fourth"; "Fifth"
       "Sixth"; "Seventh"; "Eighth"; "Ninth"; "Tenth" |]

let copiedOrdinals: string [] = Array.zeroCreate ordinals.Length

let copyOperation = StringCopy copyStrings

copyOperation.Invoke(ordinals, copiedOrdinals, 3, 5)

for ordinal in copiedOrdinals do
    printfn "%s" (if String.IsNullOrEmpty ordinal then "<None>" else ordinal)

Delegate Sub StringCopy(stringArray1() As String, _
                        stringArray2() As String, _
                        indexToStart As Integer, _
                        numberToCopy As Integer)

Module TestDelegate
    Public Sub RunIt()
        Dim ordinals() As String = {"First", "Second", "Third", "Fourth",
                                  "Fifth", "Sixth", "Seventh", "Eighth",
                                  "Ninth", "Tenth"}
        Dim copiedOrdinals(ordinals.Length - 1) As String
        Dim copyOperation As StringCopy = AddressOf CopyStrings
        copyOperation(ordinals, copiedOrdinals, 3, 5)

        Console.WriteLine()
        For Each ordinal As String In copiedOrdinals
            If String.IsNullOrEmpty(ordinal) Then
                Console.WriteLine("<None>")
            Else
                Console.WriteLine(ordinal)
            End If
        Next
    End Sub

    Private Sub CopyStrings(source() As String, target() As String, _
                           startPos As Integer, number As Integer)
      If source.Length <> target.Length Then 
         Throw New IndexOutOfRangeException("The source and target arrays" & _
                   " must have the same number of elements.")
      End If
      For ctr As Integer = startPos to startpos + number  - 1
            target(ctr) = source(ctr)
        Next
   End Sub
End Module

以下範例簡化了此程式碼，透過實 Action<T1,T2,T3,T4> 例化代理，而非明確定義新代理並指派命名方法。

using System;

public class TestAction4
{
    public static void Main()
    {
        string[] ordinals = ["First", "Second", "Third", "Fourth", "Fifth",
                           "Sixth", "Seventh", "Eighth", "Ninth", "Tenth"];
        string[] copiedOrdinals = new string[ordinals.Length];
        Action<string[], string[], int, int> copyOperation = CopyStrings;
        copyOperation(ordinals, copiedOrdinals, 3, 5);

        Console.WriteLine();
        foreach (string ordinal in copiedOrdinals)
            Console.WriteLine(string.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
    }

    private static void CopyStrings(string[] source, string[] target,
                                    int startPos, int number)
    {
        if (source.Length != target.Length)
            throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

        for (int ctr = startPos; ctr <= startPos + number - 1; ctr++)
            target[ctr] = source[ctr];
    }
}

open System

let copyStrings (source: string []) (target: string []) startPos number =
    if source.Length <> target.Length then
        raise (IndexOutOfRangeException "The source and target arrays must have the same number of elements.")

    for i = startPos to startPos + number - 1 do
        target.[i] <- source.[i]

let ordinals =
    [| "First"; "Second"; "Third"; "Fourth"; "Fifth"
       "Sixth"; "Seventh"; "Eighth"; "Ninth"; "Tenth" |]

let copiedOrdinals: string [] = Array.zeroCreate ordinals.Length

let copyOperation = Action<_, _, _, _> copyStrings

copyOperation.Invoke(ordinals, copiedOrdinals, 3, 5)

for ordinal in copiedOrdinals do
    printfn "%s" (if String.IsNullOrEmpty ordinal then "<None>" else ordinal)

Module TestAction4
    Public Sub RunIt()
        Dim ordinals() As String = {"First", "Second", "Third", "Fourth",
                                  "Fifth", "Sixth", "Seventh", "Eighth",
                                  "Ninth", "Tenth"}
        Dim copiedOrdinals(ordinals.Length - 1) As String
        Dim copyOperation As Action(Of String(), String(), Integer, Integer) =
                           AddressOf CopyStrings
        copyOperation(ordinals, copiedOrdinals, 3, 5)

        Console.WriteLine()
        For Each ordinal As String In copiedOrdinals
            If String.IsNullOrEmpty(ordinal) Then
                Console.WriteLine("<None>")
            Else
                Console.WriteLine(ordinal)
            End If
        Next
    End Sub

    Private Sub CopyStrings(source() As String, target() As String, _
                           startPos As Integer, number As Integer)
      If source.Length <> target.Length Then 
         Throw New IndexOutOfRangeException("The source and target arrays" & _
                   " must have the same number of elements.")
      End If
      For ctr As Integer = startPos to startpos + number  - 1
            target(ctr) = source(ctr)
        Next
   End Sub
End Module

你也可以在 C# 中用匿名方法使用 Action<T1,T2,T3,T4> 代理，如下範例所示。（關於匿名方法的入門，請參見匿名方法。）

using System;

public class TestAnonymousMethod
{
    public static void Main()
    {
        string[] ordinals = ["First", "Second", "Third", "Fourth", "Fifth",
                           "Sixth", "Seventh", "Eighth", "Ninth", "Tenth"];
        string[] copiedOrdinals = new string[ordinals.Length];
        Action<string[], string[], int, int> copyOperation =
                                             delegate (string[] s1, string[] s2,
                                             int pos, int num)
                                  { CopyStrings(s1, s2, pos, num); };
        copyOperation(ordinals, copiedOrdinals, 3, 5);

        Console.WriteLine();
        foreach (string ordinal in copiedOrdinals)
            Console.WriteLine(string.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
    }

    private static void CopyStrings(string[] source, string[] target,
                                    int startPos, int number)
    {
        if (source.Length != target.Length)
            throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

        for (int ctr = startPos; ctr <= startPos + number - 1; ctr++)
            target[ctr] = source[ctr];
    }
}

你也可以將 lambda 運算式指派給 Action<T1,T2,T3,T4> 代理實例，如下範例所示。（關於 lambda 表達式的入門，請參見 Lambda 表達式（C#）或 Lambda 表達式（F#）。）

using System;

public class TestLambdaExpression
{
    public static void Main()
    {
        string[] ordinals = ["First", "Second", "Third", "Fourth", "Fifth",
                           "Sixth", "Seventh", "Eighth", "Ninth", "Tenth"];
        string[] copiedOrdinals = new string[ordinals.Length];
        Action<string[], string[], int, int> copyOperation = (s1, s2, pos, num)
                                             => CopyStrings(s1, s2, pos, num);
        copyOperation(ordinals, copiedOrdinals, 3, 5);

        Console.WriteLine();
        foreach (string ordinal in copiedOrdinals)
            Console.WriteLine(string.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
    }

    private static void CopyStrings(string[] source, string[] target,
                                    int startPos, int number)
    {
        if (source.Length != target.Length)
            throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

        for (int ctr = startPos; ctr <= startPos + number - 1; ctr++)
            target[ctr] = source[ctr];
    }
}

open System

let copyStrings (source: string []) (target: string []) startPos number =
    if source.Length <> target.Length then
        raise (IndexOutOfRangeException "The source and target arrays must have the same number of elements.")

    for i = startPos to startPos + number - 1 do
        target.[i] <- source.[i]

let ordinals =
    [| "First"; "Second"; "Third"; "Fourth"; "Fifth"
       "Sixth"; "Seventh"; "Eighth"; "Ninth"; "Tenth" |]

let copiedOrdinals: string [] = Array.zeroCreate ordinals.Length

let copyOperation = Action<_, _, _, _> (fun s1 s2 pos num -> copyStrings s1 s2 pos num)

copyOperation.Invoke(ordinals, copiedOrdinals, 3, 5)

for ordinal in copiedOrdinals do
    printfn "%s" (if String.IsNullOrEmpty ordinal then "<None>" else ordinal)

Public Module TestLambdaExpression
    Public Sub RunIt()
        Dim ordinals() As String = {"First", "Second", "Third", "Fourth", "Fifth",
                           "Sixth", "Seventh", "Eighth", "Ninth", "Tenth"}
        Dim copiedOrdinals(ordinals.Length - 1) As String
        Dim copyOperation As Action(Of String(), String(), Integer, Integer) =
                           Sub(s1, s2, pos, num) CopyStrings(s1, s2, pos, num)
        copyOperation(ordinals, copiedOrdinals, 3, 5)

        Console.WriteLine()
        For Each ordinal As String In copiedOrdinals
            If String.IsNullOrEmpty(ordinal) Then
                Console.WriteLine("<None>")
            Else
                Console.WriteLine(ordinal)
            End If
        Next
    End Sub

    Private Function CopyStrings(source() As String, target() As String,
                                startPos As Integer, number As Integer) As Integer
        If source.Length <> target.Length Then
            Throw New IndexOutOfRangeException("The source and target arrays must have the same number of elements.")
        End If

        For ctr As Integer = startPos To startPos + number - 1
            target(ctr) = source(ctr)
        Next
        Return number
    End Function
End Module

' The example displays the following output:
'       Fourth
'       Fifth
'       Sixth
'       Seventh
'       Eighth

擴充方法

名稱	Description
GetMethodInfo(Delegate)	取得一個代表指定代理所代表方法的物件。

適用於

另請參閱

Func<T1,T2,T3,T4,TResult>

意見反應

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