Not sure if only a typo here or a typo in your project as well but...
If you had formatted properly, you would have found:
string str = "User ID=username;Password=password;Data Source=Test";
OracleConnection conn = new OracleConnection(str);
OracleCommand cmd = new OracleCommand("stored_procedure_name", conn);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("pv_look_up_code", "varchar2").Value = "HR";
cmd.Parameters.Add("pv_filter1", "varchar2").Value = null;
cmd.Parameters.Add("pv_filter2", "varchar2").Value = null;
cmd.Parameters.Add("pv_filter3, "varchar2").Value = null;
cmd.Parameters.Add("pv_user_id", "varchar2").Value = 1;
cmd.Parameters.Add("pv_app_code", "varchar2").Value = 1;
cmd.Parameters.Add("p_cur_list", "refcurser").Direction = ParameterDirection.InputOutput;
cmd.Parameters.Add("pn_error_code", "decimal").Direction = ParameterDirection.Output;
cmd.Parameters.Add("pv_err_text", "varchar2").Direction = ParameterDirection.IOutput;
cmd.Parameters.Add("pv_err_text_eng", "varchar2").Direction = ParameterDirection.Output;
OracleDataAdapter da = new OracleDataAdapter();
conn.Open();
da.SelectCommand = cmd;
DataSource ds = new DataSource();
da.Fill(ds);
and it should be...
string str = "User ID=username;Password=password;Data Source=Test";
OracleConnection conn = new OracleConnection(str);
OracleCommand cmd = new OracleCommand("stored_procedure_name", conn);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("pv_look_up_code", "varchar2").Value = "HR";
cmd.Parameters.Add("pv_filter1", "varchar2").Value = null;
cmd.Parameters.Add("pv_filter2", "varchar2").Value = null;
cmd.Parameters.Add("pv_filter3", "varchar2").Value = null;
cmd.Parameters.Add("pv_user_id", "varchar2").Value = 1;
cmd.Parameters.Add("pv_app_code", "varchar2").Value = 1;
cmd.Parameters.Add("p_cur_list", "refcurser").Direction = ParameterDirection.InputOutput;
cmd.Parameters.Add("pn_error_code", "decimal").Direction = ParameterDirection.Output;
cmd.Parameters.Add("pv_err_text", "varchar2").Direction = ParameterDirection.IOutput;
cmd.Parameters.Add("pv_err_text_eng", "varchar2").Direction = ParameterDirection.Output;
OracleDataAdapter da = new OracleDataAdapter();
conn.Open();
da.SelectCommand = cmd;
DataSource ds = new DataSource();
da.Fill(ds);