DataTable dt = new DataTable("image");
        DataColumn dc1, dc2;
        dc1 = new DataColumn("row", System.Type.GetType("System.Int32"));
        dc1.AutoIncrement = true;
        dc1.AutoIncrementSeed = 1;
        dc1.AutoIncrementStep = 1;
        dt.Columns.Add(dc1);

        dc2 = new DataColumn("catalog_id", System.Type.GetType("System.Int32"));
        dt.Columns.Add(dc2);

        DataRow dr1 = dt.NewRow();
        dr1["catalog_id"] = 41;
        dt.Rows.Add(dr1);

        DataRow dr2 = dt.NewRow();
        dr2["catalog_id"] = 21;
        dt.Rows.Add(dr2);

        DataRow dr3 = dt.NewRow();
        dr3["catalog_id"] = 55;
        dt.Rows.Add(dr3);

        DataRow dr4 = dt.NewRow();
        dr4["catalog_id"] = 33;
        dt.Rows.Add(dr4);

        GridView1.DataSource = dt;
        GridView1.DataBind();

        string id = "";

        for (int i = 0, max = dt.Rows.Count; i < max; i++)
        {
            id += dt.Rows[i]["catalog_id"].ToString() + ",";
        }
        id = id.Substring(0, id.Length - 1);
        Response.Write(id);

------解决方案--------------------
 string PurviewIdstr = ",";
                       for (int j = 0; j < cb_purview.Items.Count; j++)
                       {
                           if (cb_purview.SelectedValue == "")
                           {
                               HongShangProject.Common.MessageBox.Show(this, "未选择任何权限,请选择！");
                           }
                           else
                           {
                               if (cb_purview.Items[j].Selected)
                               {
                                   int _pid = 0;
                                   int.TryParse(cb_purview.Items[j].Value.Trim(), out _pid);
                                   PurviewIdstr += _cid + "-" + _pid + ",";
                               }
                           }
                       }

------解决方案--------------------
缺少
C# code
using System.Data;