c# - How to add multiple items to a list

Generic List AddRange() Method

.Net framework generic list AddRange() method allow us to add the elements of the specified collection to the end of the List<T>. the List class AddRange(T) method exists under System.Collections.Generic namespace. this method require to pass a parameter named 'collection'. the 'collection' parameter value type is System.Collections.Generic.IEnumerable<T>.

the IEnumerable<T> represents the collection whose elements should be added to the end of the List<T>. this collection itself cannot be null, but it can contain elements that are null, if type 'T' is a reference type. the AddRange() method throw an exception named ArgumentNullException if the method passed collection is null. the collection elements order is preserved in the List<T>.

the following asp.net c# example code demonstrate us how can add a collection of elements to the end of a generic list in an asp.net application.

GenericListAddRangeMethod.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("Orchid");
        colors.Add("ForestGreen");
        colors.Add("DodgerBlue");
        colors.Add("YellowGreen");

        List<string> redColors = new List<string>();
        redColors.Add("Red");
        redColors.Add("DarkRed");
        redColors.Add("IndianRed");

        colors.AddRange(redColors);
        
        RadioButtonList1.DataSource = colors;
        RadioButtonList1.DataBind();
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>Generic List AddRange() - How to add the elements of the specified collection to the end of List</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h2 style="color:DarkBlue; font-style:italic;">
            System.Collections.Generic.List AddRange() method
            <br /> How to add the elements of the specified collection to the end of List
        </h2>
        <hr width="675" align="left" color="SkyBlue" />
        <asp:RadioButtonList
             ID="RadioButtonList1"
             runat="server"
             BorderWidth="2"
             BorderColor="Navy"
             BorderStyle="Dashed"
             Font-Names="Comic Sans MS"
             Font-Italic="true"
             ForeColor="Snow"
             BackColor="MidnightBlue"
             Width="450"
             RepeatColumns="2"
             >
        </asp:RadioButtonList>
        <br />
        <asp:Button 
            ID="Button1"
            runat="server"
            OnClick="Button1_Click"
            Text="Create Generic List And Add Elements And Populate RadioButtonList"
            Height="45"
            Font-Bold="true"
            ForeColor="DodgerBlue"
            />
    </div>
    </form>
</body>
</html>

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