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

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))

Parameters

Exceptions

Examples

The following example demonstrates the use of the Action<T> delegate to print the contents of a List<T> object. In this example the Print method is used to display the contents of the list 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.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

Remarks

The Action<T> is a delegate to a method that performs an action on the object passed to it. The elements of the current List<T> are individually passed to the Action<T> delegate.

This method is an O(n) operation, where n is Count.

Modifying the underlying collection in the body of the Action<T> delegate is not supported and causes undefined behavior.

Applies to

See also

• Action<T>