空引用异常 - 查询字符串 [英] Null reference exception - Query string
问题描述
嗨....
我总是被空引用异常所困扰!
你能告诉我什么吗?我的代码在下面给出了错误?我得到
引用未设置为对象实例的错误。
protected void Page_Load(object sender,EventArgs e)
{
String myItem;
if(Request.QueryString [" Item"]。ToString()!= null)
{
myItem = Request.QueryString [" Item"]。ToString();
Label1.Text = myItem;
}
else
{
Label1.Text =" none";
}
}
谢谢!
Hi ....
I''m always getting stuck with null reference exceptions !
Can you tell me what''s wrong with my code given below ? I''m getting
the error that reference is not set to an instance of an object.
protected void Page_Load(object sender, EventArgs e)
{
String myItem;
if (Request.QueryString["Item"].ToString() != null)
{
myItem = Request.QueryString["Item"].ToString();
Label1.Text = myItem;
}
else
{
Label1.Text = "none";
}
}
Thanks !
推荐答案
Zeba< co ****** @ gmail.comwrote:
Zeba <co******@gmail.comwrote:
我总是陷入空引用异常!
你能告诉我什么吗?我的代码在下面给出了错误?我得到
引用未设置为对象实例的错误。
I''m always getting stuck with null reference exceptions !
Can you tell me what''s wrong with my code given below ? I''m getting
the error that reference is not set to an instance of an object.
在哪一行?如果它是一个有多个表达式的行,你有没有把b
$ b分解成多行,这样你就可以找到确切的
哪个表达式为空?
-
Jon Skeet - < sk *** @ pobox.com>
http://www.pobox.com/~skeet 博客: http://www.msmvps.com/jon.skeet
如果回复该群组,请不要给我发邮件太
On which line? If it''s a line with multiple expressions on, have you
tried breaking it down into multiple lines so you can find out exactly
which expression is null?
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
" Zeba" < co ****** @ gmail.comschreef in bericht
新闻:11 ********************** @ q2g2000cwa .googlegro ups.com ...
"Zeba" <co******@gmail.comschreef in bericht
news:11**********************@q2g2000cwa.googlegro ups.com...
嗨....
我总是被卡住了引用异常!
你能告诉我下面给出的代码有什么问题吗?我得到
引用未设置为对象实例的错误。
protected void Page_Load(object sender,EventArgs e)
{
String myItem;
if(Request.QueryString [" Item"]。ToString()!= null)
{
myItem = Request.QueryString [" Item"]。ToString();
Label1.Text = myItem;
}
其他
{
Label1.Text =" none";
}
}
谢谢!
Hi ....
I''m always getting stuck with null reference exceptions !
Can you tell me what''s wrong with my code given below ? I''m getting
the error that reference is not set to an instance of an object.
protected void Page_Load(object sender, EventArgs e)
{
String myItem;
if (Request.QueryString["Item"].ToString() != null)
{
myItem = Request.QueryString["Item"].ToString();
Label1.Text = myItem;
}
else
{
Label1.Text = "none";
}
}
Thanks !
可能Request.QueryString [" Item"]的计算结果为null。
您最好更改代码:
protected void Page_Load(object sender,EventArgs e)
{
String myItem;
if(Request.QueryString [" Item"]!= null)
{
myItem = Reques t.QueryString [" Item"]。ToString();
Label1.Text = myItem;
}
else
{
Label1.Text =" none";
}
}
或以这种方式保存一些字节:
protected void Page_Load(object sender,EventArgs e)
{
Label1。 Text = Request.QueryString [" Item"]!= null?
Request.QueryString [" Item"]。ToString():" none";
}
问候,
安妮
Hi,
Probably Request.QueryString["Item"] evaluates to null.
You better change your code in something like:
protected void Page_Load(object sender, EventArgs e)
{
String myItem;
if(Request.QueryString["Item"] != null)
{
myItem = Request.QueryString["Item"].ToString() ;
Label1.Text = myItem ;
}
else
{
Label1.Text = "none";
}
}
or save some bytes this way:
protected void Page_Load(object sender, EventArgs e)
{
Label1.Text = Request.QueryString["Item"] != null ?
Request.QueryString["Item"].ToString() : "none";
}
Regards,
Anne
Okayy ..!这已经解决了问题......所以是ToString()这是抱怨空引用对象的b / b
不是..
谢谢!
Okayy..! That has solved the problem...So it was ToString() which was
complaining of null reference object, wasn''t it..
Thanks !
可能Request.QueryString [" Item"]的计算结果为null。
你更好地改变你的代码如下:
protected void Page_Load(object sender,EventArgs e)
{
String myItem;
if(Request.QueryString [" Item"]!= null)
{
myItem = Request.QueryString [" Item" ] .ToString();
Label1.Text = myItem;
}
else
{
Label1.Text =" none";
}
}
或保存这样一些字节:
protected void Page_Load(object sender,EventArgs e)
{
Label1.Text = Request。 QueryString [" Item"]!= null ?
Request.QueryString [" Item"]。ToString():" none";
}
问候,
Anne
Hi,
Probably Request.QueryString["Item"] evaluates to null.
You better change your code in something like:
protected void Page_Load(object sender, EventArgs e)
{
String myItem;
if(Request.QueryString["Item"] != null)
{
myItem = Request.QueryString["Item"].ToString() ;
Label1.Text = myItem ;
}
else
{
Label1.Text = "none";
}
}
or save some bytes this way:
protected void Page_Load(object sender, EventArgs e)
{
Label1.Text = Request.QueryString["Item"] != null ?
Request.QueryString["Item"].ToString() : "none";
}
Regards,
Anne
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