类类型作为方法的参数时,使用 ref 和不使用ref的区别?..请高手解答,顶都有分
yeerh 2006-09-06 11:52:13 请先看程序:
using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
namespace Refesh
{
class Program
{
static void Main(string[] args)
{
SqlConnection conn = new SqlConnection("server=localhost;DataBase=ABC;uid=sa;pwd=password;");
DataTable dt = new DataTable("ABC");
setConn(conn);
Console.WriteLine(conn.ConnectionString);
setConn(ref conn);
Console.WriteLine(conn.ConnectionString);
setDataTable(dt);
Console.WriteLine(dt.TableName);
setDataTable(ref dt);
Console.WriteLine(dt.TableName);
Console.ReadLine();
}
static void setDataTable(DataTable dt)
{
dt = null;
dt = new DataTable("XYZ");
}
static void setDataTable(ref DataTable dt)
{
dt = null;
dt = new DataTable("XYZ");
}
static void setConn (SqlConnection conn)
{
conn = null;
conn = new SqlConnection("server=localhostSSS;DataBase=XYZ;uid=saS;pwd=XXX;");
}
static void setConn(ref SqlConnection conn)
{
conn = null;
conn = new SqlConnection("server=localhostSSS;DataBase=XYZ;uid=saS;pwd=XXX;");
}
}
}
想一下会输出什么结果....