List<T>.ForEach(Action<T>) List<T>.ForEach(Action<T>) List<T>.ForEach(Action<T>) List<T>.ForEach(Action<T>) Method

定义

List<T> 的每个元素执行指定操作。Performs the specified action on each element of the List<T>.

public:
 void ForEach(Action<T> ^ action);
public void ForEach (Action<T> action);
member this.ForEach : Action<'T> -> unit
Public Sub ForEach (action As Action(Of T))

参数

action
Action<T> Action<T> Action<T> Action<T>

要对 Action<T> 的每个元素执行的 List<T> 委托。The Action<T> delegate to perform on each element of the List<T>.

异常

已修改集合中的某个元素。An element in the collection has been modified.

示例

下面的示例演示如何使用Action<T>委托打印List<T>对象的内容。The following example demonstrates the use of the Action<T> delegate to print the contents of a List<T> object. 在此示例中Print , 方法用于将列表的内容显示到控制台。In this example the Print method is used to display the contents of the list to the console.

备注

除了使用Print方法显示内容, 该C#示例还演示了如何使用匿名方法将结果显示到控制台。In addition to displaying the contents using the Print method, the C# example demonstrates the use of anonymous methods to display the results to the console.

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<String> names = new List<String>();
        names.Add("Bruce");
        names.Add("Alfred");
        names.Add("Tim");
        names.Add("Richard");

        // Display the contents of the list using the Print method.
        names.ForEach(Print);

        // The following demonstrates the anonymous method feature of C#
        // to display the contents of the list to the console.
        names.ForEach(delegate(String name)
        {
            Console.WriteLine(name);
        });
    }

    private static void Print(string s)
    {
        Console.WriteLine(s);
    }
}
/* This code will produce output similar to the following:
 * Bruce
 * Alfred
 * Tim
 * Richard
 * Bruce
 * Alfred
 * Tim
 * Richard
 */
Imports System
Imports System.Collections.Generic

Class Program
    Shared Sub Main()
        Dim names As New List(Of String)
        names.Add("Bruce")
        names.Add("Alfred")
        names.Add("Tim")
        names.Add("Richard")

        ' Display the contents of the list using the Print method.
        names.ForEach(AddressOf Print)
    End Sub

    Shared Sub Print(ByVal s As String)
        Console.WriteLine(s)
    End Sub
End Class

' This code will produce output similar to the following:
' Bruce
' Alfred
' Tim
' Richard

注解

Action<T>是对传递给它的对象执行操作的方法的委托。The Action<T> is a delegate to a method that performs an action on the object passed to it. 当前List<T>的元素被单独传递Action<T>到委托。The elements of the current List<T> are individually passed to the Action<T> delegate.

此方法的运算复杂度为 O (n), 其中 n Count是。This method is an O(n) operation, where n is Count.

不支持修改Action<T>委托正文中的基础集合, 这会导致未定义的行为。Modifying the underlying collection in the body of the Action<T> delegate is not supported and causes undefined behavior.

适用于

另请参阅