Update submitted Perforce changelist description by P4.net api

Firstly download the p4.net sdk from Perforce official site's download page.

It's a .zip file, extract it to disk and you'll find a README.txt for how to create a .net application to use the API.

And here is the C# code to update a submitted changelist's description:

using Perforce.P4;

namespace ModifyP4CLDescription
{
    class Program
    {
        static void Main(string[] args)
        {
            string uri = "my_perforce_server:1666";
            string user = "my_user_name";
            string ws_client = "my_work_space_name";

            Server server = new Server(new ServerAddress(uri));
            Repository rep = new Repository(server);
            Connection con = rep.Connection;

            con.UserName = user;
            con.Client = new Client();
            con.Client.Name = ws_client;

            con.Connect(null);

            Changelist c = rep.GetChangelist(123456);
            string newDiscription = c.Description + "modify my description";
            c.Description = newDiscription;
            ChangeCmdOptions opts = new ChangeCmdOptions(ChangeCmdFlags.Update);
            c = rep.UpdateChangelist(c, opts);            
29         }
    }
}