C gets the stored procedure return value and the output parameter value

1. Get the return value of Return

// The stored procedure 
//Create PROCEDURE MYSQL
//     @a int,
//     @b int
//AS
//     return @a + @b
//GO
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["LocalSqlServer"].ToString());
conn.Open();
SqlCommand MyCommand = new SqlCommand("MYSQL", conn);
MyCommand.CommandType = CommandType.StoredProcedure;
MyCommand.Parameters.Add(new SqlParameter("@a", SqlDbType.Int));
MyCommand.Parameters["@a"].Value = 10;
MyCommand.Parameters.Add(new SqlParameter("@b", SqlDbType.Int));
MyCommand.Parameters["@b"].Value = 20;
MyCommand.Parameters.Add(new SqlParameter("@return", SqlDbType.Int));
MyCommand.Parameters["@return"].Direction = ParameterDirection.ReturnValue;
MyCommand.ExecuteNonQuery();
Response.Write(MyCommand.Parameters["@return"].Value.ToString());

2. Get the output parameter value of Output

// The stored procedure 
//Create PROCEDURE MYSQL
//     @a int,
//     @b int,
//     @c int output
//AS
//     Set @c = @a + @b
//GO
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["LocalSqlServer"].ToString());
conn.Open();
SqlCommand MyCommand = new SqlCommand("MYSQL", conn);
MyCommand.CommandType = CommandType.StoredProcedure;
MyCommand.Parameters.Add(new SqlParameter("@a", SqlDbType.Int));
MyCommand.Parameters["@a"].Value = 20;
MyCommand.Parameters.Add(new SqlParameter("@b", SqlDbType.Int));
MyCommand.Parameters["@b"].Value = 20;
MyCommand.Parameters.Add(new SqlParameter("@c", SqlDbType.Int));
MyCommand.Parameters["@c"].Direction = ParameterDirection.Output;
MyCommand.ExecuteNonQuery();
Response.Write(MyCommand.Parameters["@c"].Value.ToString());

C# receive stored procedure return value:

     public static int User_Add(User us)
     {
         int iRet;
         SqlConnection conn = new SqlConnection(Conn_Str);
         SqlCommand cmd = new SqlCommand("User_Add", conn);
         cmd.CommandType = CommandType.StoredProcedure;
         cmd.Parameters.AddWithValue("@UName", us.UName);
         cmd.Parameters.AddWithValue("@UPass", us.UPass);
         cmd.Parameters.AddWithValue("@PassQuestion", us.PassQuestion);
         cmd.Parameters.AddWithValue("@PassKey", us.PassKey);
         cmd.Parameters.AddWithValue("@Email", us.Email);
         cmd.Parameters.AddWithValue("@RName", us.RName);
         cmd.Parameters.AddWithValue("@Area", us.Area);
         cmd.Parameters.AddWithValue("@Address", us.Address);
         cmd.Parameters.AddWithValue("@ZipCodes", us.ZipCodes);
         cmd.Parameters.AddWithValue("@Phone", us.Phone);
         cmd.Parameters.AddWithValue("@QQ", us.QQ);
         cmd.Parameters.Add("@RETURN_VALUE", "").Direction = ParameterDirection.ReturnValue;       
         try
         {
             conn.Open();
             cmd.ExecuteNonQuery();
             iRet = (int)cmd.Parameters["@RETURN_VALUE"].Value;
         }
         catch (SqlException ex)
         {
             throw ex;
         }
         finally
         {
             conn.Close();
         }
         return iRet;
     }

C# receive stored procedure output parameters:

    public static decimal Cart_UserAmount(int UID)
    {
        decimal iRet;
        SqlConnection conn = new SqlConnection(Conn_Str);
        SqlCommand cmd = new SqlCommand("Cart_UserAmount", conn);
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Parameters.AddWithValue("@UID", UID);
        cmd.Parameters.Add("@Amount", SqlDbType.Decimal).Direction=ParameterDirection.Output;
        try
        {
            conn.Open();
            cmd.ExecuteNonQuery();
            iRet = (decimal)cmd.Parameters["@Amount"].Value;
        }
        catch (SqlException ex)
        {
            throw ex;
        }
        finally
        {
            conn.Close();
        }
        return iRet;
    }