C# 存储过程 输出参数不能返回 的问题？

using System;   
using System.Collections.Generic;   
using System.Text;   
  
using System.Data;   
using System.Data.SqlClient;   
using System.Collections;   
using HelloWinForm.DBUtility;   
using System.Windows.Forms;   
  
namespace HelloWinForm.DAL   
{   
    class Student   
    {   
        SQLHelper sqlHelper = new SQLHelper();//非静态方法,需要实例化类   
        /// <summary>   
        /// 执行带输入输出参数的存储过程   
        /// </summary>   
        /// <returns></returns>   
        public int procInAndOut()   
        {   
            SqlParameter[] paramsArr =    
            {   
                sqlHelper.MakeOutParam("@outParam" , SqlDbType.Int , 4),   
                sqlHelper.MakeInParam("@inParam" , SqlDbType.NVarChar , 50 ,"tree")   
            };   
            paramsArr[0].Direction = ParameterDirection.Output;   
            int lines = sqlHelper.RunProc("proc_InAndOut", paramsArr); //return (int)cmd.Parameters[0].Value;   
            return lines;   
        }   
        /// <summary>   
        /// 执行带输入参数的存储过程,返回DataReader,不用此法,不方法,需要再次关闭数据连接   
        /// </summary>   
        /// <returns></returns>   
        public SqlDataReader getDataReader()   
        {   
            SqlDataReader reader;   
            SqlParameter[] paramsArr =    
            {   
                sqlHelper.MakeInParam("@StudentName" , SqlDbType.NVarChar , 50 ,"tree"),   
                sqlHelper.MakeInParam("@inParam" , SqlDbType.NVarChar , 50 ,"tree")   
            };   
            sqlHelper.RunProc("proc_getDataReader", paramsArr, out reader);   
            //sqlHelper.Close();//不能在此关闭   
            return reader;   
        }   
        /// <summary>   
        /// 如果使用DataReader应该在这里执行打开和关闭.   
        /// </summary>   
        /// <returns></returns>   
        public string getDataFromReader()   
        {   
            string returnStr = "";   
            SqlDataReader reader;   
            SqlParameter[] paramsArr =    
            {   
                sqlHelper.MakeInParam("@StudentName" , SqlDbType.NVarChar , 50 ,"tree"),   
                sqlHelper.MakeInParam("@inParam" , SqlDbType.NVarChar , 50 ,"tree")   
            };   
            sqlHelper.RunProc("proc_getDataReader", paramsArr, out reader);   
            try  
            {   
                while (reader.Read())   
                {   
                    returnStr += reader.GetInt32(0);   
                    returnStr += reader.GetString(1);   
                }   
            }   
            catch (Exception ex)   
            {   
                MessageBox.Show(ex.Message);   
            }   
            finally  
            {   
                sqlHelper.Close();   
            }   
            return returnStr;   
        }   
        public string test()   
        {   
            string str = "";   
            SqlDataReader dr = SQLHelper.ExecuteReader("select * from Student");   
            while (dr.Read())   
            {   
                str += dr["StudentNO"].ToString();   
            }   
            dr.Close();   
            return str;   
        }   
        public int proc()   
        {   
            return sqlHelper.RunProc("proc_Test");   
        }   
    }   
}