集合已修改；枚举操作可能无法执行。

Question

foreach (DataRow dr in dtData.Rows.Cast<DataRow>().ToList())

Answer 1

foreach里面有代码对dtdata进行添加和移除的操作，这是不允许的。
你可以用中间变量记录一下要增加和移除的对象，循环结束后在进行添加和移除操作

Answer 2

经过#1的方法改程序后，执行到byte[] groupid = HexStrToHexBytes(dr["Group_name"].ToString());会提示错误：“此行已从表中移除并且没有任何数据。BeginEdit() 将允许在此行中创建新数据”，这是怎么回事呢？

Answer 3

你没贴完吧？是不是还有对dtData修改或者增删的代码？

Answer 4

问题比较多，有些信息你没有提供，比如：是刚进入这个 foreach 的时候报错了，还是在 foreach 内部执行到某一句话的时候报错了？代码要贴完整，有些你可能出错的都不贴出来。
而且你…………没有单步调试吗？先单步调试一下，找到真正出错的语句再说吧！

Answer 5

就是在foreach 内部执行到byte[] groupid = HexStrToHexBytes(dr["Group_name"].ToString());这句时会提示错误，单步调试也是到这步出错，这怎么回事呢？好像后面没有对dtData修改或者增删的代码了，下面我把这部分程序完整贴一下
 

Answer 6

if (EMMSEND && IfChannelSetup && IfStreamSetup)  // 时间到，通道建立，流建立
                //if (EMMSEND)
                {
                    // if (receiveflag == true)
                    // {                    string ConnMdbStr = "Data Source='" + txtsqlip.Text + "' ;Initial Catalog='" + dataname.Text + "';User ID=sa;Password='" + txtpassword.Text + "'";
                    SqlConnection ConnMdb = new SqlConnection(ConnMdbStr);
                    string SqlText = "SELECT * FROM Group_SGK3 ";
                    SqlDataAdapter da = new SqlDataAdapter(SqlText, ConnMdb);
                    try
                    {
                        //da.Fill(dt);
                        dtData.Clear();
                        da.Fill(dtData);                    }
                    catch
                    {
                        break;
                    }
                    //}                                       foreach (DataRow dr in dtData.Rows.Cast<DataRow>().ToList())     //遍历行 in 行的集合
                    {
                        byte[] EDS = new byte[183];
                        EDS[0] = 0x82;  // emm table id
                        EDS[1] = 0x40;   // 
                        EDS[2] = 0x3f;
                        EDS[3] = 0x02;// emm secton length
                        byte[] groupid = HexStrToHexBytes(dr["Group_name"].ToString());
                        EDS[4] = groupid[0];
                        EDS[5] = groupid[1];
                        // emm secton length
                        //发送emm                       
                       
                        string strConn = "Data Source=127.0.0.1;Initial Catalog=zy;User ID=sa;Password=229107my229107m";
                        SqlConnection ConnAcc = new SqlConnection(strConn);
                        string strSQL = "SELECT * FROM Group_SGK3 ";
                        SqlDataAdapter de = new SqlDataAdapter(strSQL, ConnMdb);
                        try
                        {
                            //da.Fill(dt);
                            dtData.Clear();
                            de.Fill(dtData);                        }
                        catch
                        {
                            break;
                        }
                            for (int n = 0; n < 7; n++)
                            {
                                int GK;
                                foreach (DataRow rdr in dtData.Rows)
                                {                                    int SGK = Convert.ToInt32(rdr["SGK"]);
                                    GK = SGK << n;                                    
                                        if (Convert.ToBoolean(rdr["state1"]))
                                        {
                                                                                        byte[] gk = new byte[8];
                                            Array.Copy(HexStrToHexBytes(GK.ToString()), 0, gk, 7, 1);
                                            
                                            SKeyValue = SKeyValue1;
                                            byte[] EncryptSk = EncryptDES(SKeyValue, gk);
                                                                                        EDS[6] = 0x01;
                                            Array.Copy(EncryptSk, 0, EDS, 7, EncryptSk.Length);
                                            //Thread.Sleep(5);
                                        }
                                        else
                                        {
                                            // byte[] EDS = new byte[183];                                            EDS[6] = 0x01;
                                            
                                            EDS[7] = 0xff;
                                            EDS[8] = 0xff;
                                            for (int i = 9; i < 15; i++)
                                            {
                                                EDS[i] = 0x00;                                            }                                        }
                                        if (Convert.ToBoolean(rdr["state2"]))
                                        {
                                            
                                            byte[] gk = new byte[8];
    Array.Copy(HexStrToHexBytes(GK.ToString()), 0, gk, 7, 1);// pdk buf: 0,0,0,0,0,0,0,0xcd
                                            
                                            SKeyValue = SKeyValue2;
                                            byte[] EncryptSk = EncryptDES(SKeyValue, gk);
                                           
                                            EDS[15] = 0x02;
                                            Array.Copy(EncryptSk, 0, EDS, 16, EncryptSk.Length);                                        }
                                        else
                                        {
                                           
                                            EDS[16] = 0xff;
                                            EDS[17] = 0xff;
                                            for (int i = 18; i < 24; i++)
                                            {
                                                EDS[i] = 0x00;                                            }
                                        }
                                        if (Convert.ToBoolean(rdr["state3"]))
                                        {
                                            
                                            byte[] gk = new byte[8];
      Array.Copy(HexStrToHexBytes(GK.ToString()), 0, gk, 7, 1);// pdk buf: 0,0,0,0,0,0,0,0xcd
                                           
                                            SKeyValue = SKeyValue3;
                                            byte[] EncryptSk = EncryptDES(SKeyValue, gk);
                                           
                                            EDS[24] = 0x03;
                                            Array.Copy(EncryptSk, 0, EDS, 25, EncryptSk.Length);                                        }
                                       

Answer 7

 else
                                        {                                            
                                         
                                            EDS[24] = 0x03;
                                            
                                            EDS[25] = 0xff;
                                            EDS[26] = 0xff;
                                            for (int i = 27; i < 33; i++)
                                            {
                                                EDS[i] = 0x00;                                            }                                        }
                                        if (Convert.ToBoolean(rdr["state4"]))
                                        {
                                                                                    byte[] gk = new byte[8];
             Array.Copy(HexStrToHexBytes(GK.ToString()), 0, gk, 7, 1);
                                           
                                            SKeyValue = SKeyValue4;
                                            byte[] EncryptSk = EncryptDES(SKeyValue, gk);
                                                                                        EDS[33] = 0x04;
                                            Array.Copy(EncryptSk, 0, EDS, 34, EncryptSk.Length);
                                            Thread.Sleep(5);
                                        }
                                        else
                                        {
                                            
                                           
                                            EDS[34] = 0xff;
                                            EDS[35] = 0xff;
                                            for (int i = 36; i < 42; i++)
                                            {
                                                EDS[i] = 0x00;                                            }                                        }
                                        for (int i = 42; i < 183; i++)
                                        {
                                            EDS[i] = 0xff;                                        }                MsgSend(TcpSocket, (int)Msg_Type_Value.Data_provision, SendBytes, EDS);
                                        InsertMsgLineWithTime("分组用户授权信息发送");
                                        Thread.Sleep(10);                                    }
                                
                            }
                    
                        
                      
                    }
                    string SqlTex = "SELECT * FROM User_S2 ";
                    SqlDataAdapter ds = new SqlDataAdapter(SqlTex, ConnMdb);
                    try
                    {
                        //da.Fill(dt);
                        dtData.Clear();
                        ds.Fill(dtData);
                    }
                    catch
                    {
                        break;
                    }
                    foreach (DataRow dr in dtData.Rows)
                    {
                        byte[] EDS = new byte[183];
                        EDS[0] = 0x82;  // emm table id
                        EDS[1] = 0x40;   // 
                        EDS[2] = 0x3f;
                        EDS[3] = 0x01;
                        byte[] pdk = new byte[8];
                        Array.Copy(HexStrToHexBytes(dr["pdk"].ToString()), 0, pdk, 7, 1);// pdk buf: 0,0,0,0,0,0,0,0xcd
                        byte[] sgroupid = HexStrToHexBytes(dr["SGroup_name"].ToString());
                        byte[] SGK = new byte[8];
                        Array.Copy(HexStrToHexBytes(dr["SGK"].ToString()), 0, SGK, 7, 1);
                        byte[] EncryptSk = EncryptDES(SGK, pdk);
                        byte[] sgroup_id = HexStrToHexBytes(dr["SGroup_id"].ToString());
                        EDS[4] = (byte)sgroupid[0];
                        EDS[5] = (byte)sgroupid[1];
                        EDS[6] = (byte)sgroup_id[0];
                        EDS[7] = (byte)sgroup_id[1];
                        Array.Copy(EncryptSk, 0, EDS, 8, EncryptSk.Length);
                        int i;
                        for (i = 8 + EncryptSk.Length; i < EDS.Length; i++)
                        {
                            EDS[i] = 0xff;                        }
                        MsgSend(TcpSocket, (int)Msg_Type_Value.Data_provision, SendBytes, EDS);
                        InsertMsgLineWithTime("超组用户分组数据发送");
                        Thread.Sleep(10);                    }
                    SqlText = "SELECT * FROM stack ";
                     ds = new SqlDataAdapter(SqlTex, ConnMdb);
                    try
                    {
                        //da.Fill(dt);
                        dtData.Clear();
                        ds.Fill(dtData);
                    }
                    catch
                    {
                        break;
                    }
                    foreach (DataRow dr in dtData.Rows)
                    {
                        break;
                    
                    }                    EMMSEND = false;
                }