c# - How to remove all elements from a list

Generic List Clear() Method

.Net framework generic list Clear() method allow us to remove all elements from the List<T>. the Clear() method exists in System.Collections.Generic namespace. this method require no parameter. the Clear() method implements as ICollection<T>.Clear() and IList.Clear().

the Clear() method set the Count is 0 (zero) and references to other objects from elements of the collection are also released. this method does not change the list Capacity.

the following asp.net c# example code demonstrate us how can we remove all elements from the specified generic list in an asp.net application.

GenericListClearMethod.aspx


<%@ Page Language="C#" AutoEventWireup="true" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
    protected void Button1_Click(object sender, System.EventArgs e)
    {
        List<string> colors = new List<string>();
        colors.Add("DarkOrchid");
        colors.Add("Plum");
        colors.Add("BlanchedAlmond");

        Label1.Text = "List Elements....";
        foreach(string color in colors)
        {
            Label1.Text +="<br />" + color;
        }

        colors.Clear();

        Label1.Text += "<br /><br />After Call Clear() method: List Elements....";
        foreach (string color in colors)
        {
            Label1.Text += "<br />" + color;
        }
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>Generic List Clear() - How to Remove all elements from the List</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h2 style="color:DarkGreen; font-style:italic;">
            System.Collections.Generic.List Clear() method
            <br /> How to Remove all elements from the List
        </h2>
        <hr width="475" align="left" color="Pink" />
        <asp:Label
             ID="Label1"
             runat="server"
             Font-Size="Large"
             ForeColor="SeaGreen"
             Font-Italic="true"
             >
        </asp:Label>
        <br /><br />
        <asp:Button 
            ID="Button1"
            runat="server"
            OnClick="Button1_Click"
            Text="Test Generic List Clear() Method"
            Height="45"
            Font-Bold="true"
            ForeColor="DodgerBlue"
            />
    </div>
    </form>
</body>
</html>

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