c# - How to merge two Dictionaries

Dictionary merge
dictionary-merge.aspx

<%@ Page Language="C#" AutoEventWireup="true"%>
  
<!DOCTYPE html>    
<script runat="server">  
    protected void Button1_Click(object sender, System.EventArgs e)
    {
        //initialize a dictionary with keys and values.
        Dictionary<int, string> birds = new Dictionary<int, string>() {
            {1,"Eurasian Curlew"},
            {2,"Whimbrel"},
            {3,"Greater Yellowlegs"}
        };

        Dictionary<int, string> birds2 = new Dictionary<int, string>() {
            {3,"Spotted Sandpiper"},
            {4,"Egyptian Plover"},
            {5,"Collared Pratincole"}
        };

        Label1.Text = "dictionary keys and values..........";
        foreach (KeyValuePair<int, string> pair in birds)
        {
            Label1.Text += "<br />" + pair.Key + " ........ " + pair.Value;
        }

        Label1.Text += "<br /><br />dictionary2 keys and values..........";
        foreach (KeyValuePair<int, string> pair in birds2)
        {
            Label1.Text += "<br />" + pair.Key + " ........ " + pair.Value;
        }

        Dictionary<int, string> combined = birds;
        foreach (KeyValuePair<int, string> pair in birds2)
        {
            //this line check for duplicate keys.
            if (combined.ContainsKey(pair.Key) == false)
            {
                //only unique key added in marged dictionary.
                combined.Add(pair.Key,pair.Value);
            }
        }

        Label1.Text += "<br /><br />marged dictionary keys and values..........";
        foreach (KeyValuePair<int, string> pair in combined)
        {
            Label1.Text += "<br />" + pair.Key + " ........ " + pair.Value;
        }
    }    
</script>    
    
<html xmlns="http://www.w3.org/1999/xhtml">    
<head id="Head1" runat="server">    
    <title>c# example - dictionary merge</title>    
</head>    
<body>    
    <form id="form1" runat="server">    
    <div>    
        <h2 style="color:MidnightBlue; font-style:italic;">    
            c# example - dictionary merge
        </h2>    
        <hr width="550" align="left" color="Gainsboro" />    
        <asp:Label     
            ID="Label1"     
            runat="server"    
            Font-Size="Large"  
            >    
        </asp:Label>    
        <br /><br />  
        <asp:Button     
            ID="Button1"     
            runat="server"     
            Text="dictionary merge"    
            OnClick="Button1_Click"  
            Height="40"    
            Font-Bold="true"    
            />    
    </div>    
    </form>    
</body>    
</html>
More c# examples