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Hi, I want to dispaly the time on the form. For every elapse the event should be raised. so for every 1000 milliseconds the time should be change on screen.
No other threads are running in my program...
But i getting the following error:
Cross-thread operation not valid: Control 'label1' accessed from a thread other than the thread it was created on.
please help.
Thanks in advance
private void button1_Click(object sender, EventArgs e)
{
label1.Text = Convert.ToString(DateTime.Now);
System.Timers.Timer objTimer = new System.Timers.Timer();
objTimer.Elapsed += new ElapsedEventHandler(DisplayTimeEvent);
objTimer.Interval = 1000;
objTimer.Start();
}
public void DisplayTimeEvent(object source, ElapsedEventArgs e)
{
label1.Text = Convert.ToString(DateTime.Now);
}
G. Satish
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Satish - Developer wrote: But i getting the following error:
Cross-thread operation not valid: Control 'label1' accessed from a thread other than the thread it was created on.
What you are doing wrong is that you want to change the label's text property from another thread than the one is was created on. You need to use Invoke and InvokeRequired.
I will use Google before asking dumb questions
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Fianlly i got answer by invoking the label
public void DisplayTimeEvent(object source, ElapsedEventArgs e)
{
this.label1.Invoke(
(MethodInvoker)delegate()
{
label1.Text = Convert.ToString(DateTime.Now);
}
);
}
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As Andrei has stated above, the rule is that only the thread which creates a control should update it.
You could alternatively use the System.Windows.Forms timer, as this always fires on the primary GUI thread and no thread switch is required.
Regards,
Rob Philpott.
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Finally i got the answer by invoking the Label. Thank u
public void DisplayTimeEvent(object source, ElapsedEventArgs e)
{
this.label1.Invoke(
(MethodInvoker)delegate()
{
label1.Text = Convert.ToString(DateTime.Now);
}
);
}
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I have this application that sends mail to a mail server.The server uses Domino Lotus iNote to distribute and display the mails.But when a user receives the mail,the column that suppose to show the "Who" is always blank/empty making the mail look more like a spam.And some users don't care to open it thinking that it is a spam.
Can anyone help me out with how to fill this "Who" column.
I use:
MailMessage myMail = new MailMessage();
myMail.From = "myname@me.com";
myMail.To = "emailTxt.Text";
myMail.Fields.Add("SenderName","myname");
myMail.Subject = "You Have Been Appraised!";
myMail.BodyFormat = MailFormat.Text;
myMail.Body = "Go and confirm or contest your mail! ";
SmtpMail.SmtpServer = "10.12.19.105";
SmtpMail.Send(myMail);
I don't know if there is another parameter that is required to be able to send an email to domino lotus iNote.
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Hi I need to get the Focused Property of My ListBox list from within a thread. The thread makes calls to following function
<br />
bool listFocused()<br />
{<br />
if (this.list.InvokeRequired)<br />
{<br />
ListFocusCallBack d = new ListFocusCallBack(listFocused);<br />
Object obj = this.list.Invoke(d, new object[] {});<br />
}<br />
else<br />
{<br />
return this.list.Focused;<br />
}<br />
}<br />
If I compile the above then I get a "not all code paths return a value" error, because I'm not returning anything in "ProblemLine"
I tried replacing "ProblemLine" with
if( obj.Equals(Boolean.TrueString ))<br />
return true;<br />
return false;<br />
but I'm not sure if it is the right approach.
Please Advice
Thanks...
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Hello,
You don't need the else statement in your method.
If invoke is called the code after that will not been worked threw.
Set a breakpoint at the first line of the method and Debug it to see it better.
Your method could look like that:
bool listFocused()
{
if(this.list.InvokeRequired)
{
ListFocusCallBack d = new ListFocusCallBack(listFocused);
this.list.Invoke(d, new object[] {});
}
return this.list.Focused;
}
-- modified at 8:07 Wednesday 21st November, 2007
Wrong Information Sorry
All the best,
Martin
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To my knowledge, it's not thread safe this way, let me explain :
bool listFocused()
{
if(this.list.InvokeRequired)
{
ListFocusCallBack d = new ListFocusCallBack(listFocused);
this.list.Invoke(d, new object[] {});
}
return this.list.Focused;
}
what you need to do is to return value that Control.Invoke method returns
bool listFocused()
{
if(this.list.InvokeRequired)
{
ListFocusCallBack d = new ListFocusCallBack(listFocused);
return (bool)this.list.Invoke(d, new object[] {});
}
else
{
return this.list.Focused;
}
}
zilo
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Hello Zilo,
I do not agree with you.
Zilo(svk) wrote: return this.list.Focused; // !!! again [T1] - if u invoke a delegate using control invoke, it doesn't mean // that the rest of this method will be executed on that invoked thread. it // remains on thread [T1], where it's not safe to get the Focused value.
This code will never be executed by [T1] AFAIK.
After the Invoke call, the method will no longer go threw the rest of the method code.
I often debugged such a situation, and hope what I just told is not complete rubbish!
-- modified at 8:09 Wednesday 21st November, 2007
I wrote: hope what I just told is not complete rubbish
It was rubbish!
All the best,
Martin
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Test it. It really is the way I wrote. I mean I don't see any reason why Control.Invoke(delegate Method); should for any reason make calling method to return whatever the delegate returns. It does just doesn't make any sense. Execution continues. It just blocks until delegate completed.
zilo
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Hello Zilo,
Just testet it, and have to say THANK YOU SO MUCH for pointing that out.
First of all, I was not consistend in my Projects.
And second, I was completely wrong.
Thats what I like at CP.
By answering (or trying to do so at least), you also get support!
Got my '5'.
Thanks again!
All the best,
Martin
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np,
It's good to know that you know something  ) . I wasn't sure either about this one.
zilo
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I was also thinking on similar lines what I actually did was
<br />
if (this.list.InvokeRequired)<br />
{<br />
ListFocusCallBack d = new ListFocusCallBack(listFocused);<br />
Object obj = this.list.Invoke(d, new object[] {});<br />
<br />
if( obj.Equals(Boolean.TrueString ))<br />
return true;<br />
return false;<br />
}<br />
else<br />
{<br />
return this.list.Focused;<br />
}<br />
Your solution about converting Object to bool as (bool)obj never came to my mind. I never knew it was possible.
Thanks...
The Show Ain't Over Yet...
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it send data to tcp/ip port number, ex 8080, now i want to write socket program to read data from that port. Any body help me? How can i do that?
plz post the code
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No more comment!
All the best,
Martin
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Couldn't agree more....
Standards are great! Everybody should have one!
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Try here [^]. You will surely get the kind of help you want.
I will use Google before asking dumb questions
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I'm doing this just to prevent you from posting continuous new threads on this forum. Use this [link] . It an old post of mine to another problem, there you have a code sample to get you started. And next time search CodeProject and Google, get you hands dirty and when you're stuck come here and post question; if you want code use the link I gave you earlier.
I will use Google before asking dumb questions
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I'm sorry, but which bit of we aren't here to do your job for you is so hard to understand? If you can't cope with a task like this, with the advice you've already been given, then I would consider a career change to one where the only questions you need to ask is
"Do you want fries with that?"
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Pete O`Hanlon wrote: f you can't cope with a task like this, with the advice you've already been given, then I would consider a career change to one where the only questions you need to ask is
"Do you want fries with that?"
Nice one. 
I will use Google before asking dumb questions
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"More functions should disregard input values and just return 12. It would make life easier." - comment posted on WTF
"This time yesterday, I still had 24 hours to meet the deadline I've just missed today."
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Hello
I'm stuck with a C++ (or something) Dll that i'm supposed to call from a c# App.
(or even "better" from a vb.net app  )
The header file says something like
int Initialize([in]unsigned int SlotID, [in]unsigned char* Label, [in]unsigned char* Pin, [in/out]void* hSession);
this
[DllImport("MyDll.dll",EntryPoint="Initialize", ExactSpelling=true, SetLastError=true)]
private extern static void Init(uint SlotID, string Label, string Pin, out IntPtr Handle);
doesn't work at all. it tells me that the target caused an error.
now i tried to marshal the types like
[DllImport("MyDll.dll",EntryPoint="Initialize", ExactSpelling=true, SetLastError=true)]
private extern static void Init([MarshalAs(UnmanagedType.U4)]uint SlotID, [MarshalAs(UnmanagedType.LPStr)]string Label, [MarshalAs(UnmanagedType.LPStr)]string Pin, out IntPtr Handle);
this gives me an Access Violation and marshalling the strings as LPTStr isn't any better.
my last try to build a fixedString struct for passing to that method
[StructLayout(LayoutKind.Sequential)]
private struct fixedString
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst=23)]
string MyString;
}
[DllImport("MyDll.dll",EntryPoint="Initialize", ExactSpelling=true, SetLastError=true)]
private extern static void Init([MarshalAs(UnmanagedType.U4)]uint SlotID, fixedString Label, fixedString Pin, out IntPtr Handle);
well you know... *sigh*
i even tried to make it work with unsave coding but still got access-violations or just with that TargetInvocationException
does anybody have an idea how i could get that thing to work?
thanks in advance
greets
m@u
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If any strings get changed in the unmanaged code you have to use a StringBuilder object.
"More functions should disregard input values and just return 12. It would make life easier." - comment posted on WTF
"This time yesterday, I still had 24 hours to meet the deadline I've just missed today."
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