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Hello, this may be a stupid question but I'm curious. I have a class I've created (that extends the FORM class) that runs as a child form of my main application. The purpose and nature of the form is such that it doesn't matter if it closes...the parent form monitors and will reopen it if necessary. I am handling several types of exceptions and closing the child form when they occur. However, I occasionally get an unhandled exception (in the child form) that causes it to crash.
I'm looking for a way to catch all unhandled exceptions in my custom class and run an event accordingly. Is there a way to do this? I see a method for any unhandled exceptions for the whole app, but I don't want that. I also see how to handle all exceptions when my child form is initialized, but that doesn't help if it's already initialized and running.
All I want now is to handle all exceptions in my custom class. Is this possible?
Thanks,
Alan
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You can put a try block where your form gets started.
<br />
<br />
try<br />
{<br />
Application.Run(new Form1());<br />
}<br />
catch (Exception ex)<br />
{<br />
LogException(ex);<br />
Application.Exit();<br />
}<br />
<br />
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eggs,
thanks for the suggestion! i believe that code will catch any unhandled exceptions generated by my entire app (parent form, and my custom child form). i'm trying to just catch errors in the child form.
the child form is being added something like this:
<br />
frmCustomForm = new MyCustomForm();<br />
<br />
this.Controls.Add(frmCustomForm);
i would like any unhandled exception that occurs within that custom form to cause it to trigger an event.
alan
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Here's an idea of what you could do (although I make no assurances as to the quality of the the design!  ) -
In your custom form you'll need to surround any potentially error producing blocks of code in a standard try...catch block. What you'll also need in the custom class is an event, perhaps call it OnError or similar (have a google for how events are implemented in C#), and when an error is caught by the try...catch mechanism, fire off the OnError event.
Then from your main app you can subscribe to this event with something like the following:
{...
frmCustomForm = new MyCustomForm();
frmCustomForm.OnError += new EventHandler(yourMethodHere);
this.Controls.Add(frmCustomForm);
...}
private void yourMethodHere()
{
code that runs when the event is fired an recieved.
}
Now a word of warning It sounds as if there's a lot of logic contained in your custom form that might suit being refactored out... something for you to have a think about!
"On one of my cards it said I had to find temperatures lower than -8. The numbers I uncovered were -6 and -7 so I thought I had won, and so did the woman in the shop. But when she scanned the card the machine said I hadn't.
"I phoned Camelot and they fobbed me off with some story that -6 is higher - not lower - than -8 but I'm not having it."
-Tina Farrell, a 23 year old thicky from Levenshulme, Manchester.
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Thanks for all of the suggestions. I ended up using pretty much all of them in some form or another. I've isolated this custom class to run as a Windows service, and handle all UI and non UI unhandled exceptions with global handlers under Main().
Alan
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Hi All,
I can't find any good examples of throwing exceptions. I have the following code. I want to include all the possible exceptions i can. Help me out on this. I am just moving away from console object and moving towards exception object.
public int DeleteFilesOlderThan(int Days, int Hrs, int Mins, string filter)
{
DateTime dt = GetRelativeDateTime(Days, Hrs, Mins);
ArrayList oldFilePaths = FilesOlderThan(dt, filter);
int count = 0;
string message = null;
foreach (string filePath in oldFilePaths)
{
try
{
File.Delete(filePath);
count++;
}
//* System.Exception is too general..I want something more like FileNotFoundException...any exception that can be related to my code
catch (Exception e)
{
message = "Unable to delete " + filePath + "\r\n";
message += String.Format("Reason: {0}", e.Message);
MessageBox.Show(message);
}
}
return count;
}
// Using GetRelativeDateTime as a private method instead of public however as it is only to be used internally
private static DateTime GetRelativeDateTime(int days, int hours, int minutes)
{
return DateTime.Now.AddDays(-days).AddHours(-hours).AddMinutes(-minutes);
}
public ArrayList FilesOlderThan(DateTime dt, string filter)
{
//m_FolderPath = @"C:\CsharpTempFolder";
// Using the supplied path
//DirectoryInfo directory = new DirectoryInfo(Directory.GetCurrentDirectory())
DirectoryInfo directory = new DirectoryInfo(m_FolderPath);
// Filter is applied to the directory.GetFiles method to get files of given extension
// get FileInfos for the files in the current directory matching the filter expression
FileInfo[] files = directory.GetFiles(filter);
//list to hold the result
ArrayList older = new ArrayList();
foreach (FileInfo file in files)
{
//if smaller (older) than the relative time
if (file.CreationTime < dt)
older.Add(file.FullName); //add it to the list
}
return older;
}
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A try block can have multiple catch blocks. These should be arranged t-b in decdending order of specificity. You could have a block to specifically catch the FileNotFoundException exception, followed by a general block to catch any exceptions that derive from System.Exception. If an exception is raised, execution will branch into the first relevent catch block.
Paul Marfleet
"No, his mind is not for rent
To any God or government"
Tom Sawyer - Rush
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So, is that it then?
catch (FileNotFoundException e)
{
message = "Unable to delete " + filePath + "\r\n";
message += String.Format("Reason: {0}", e.Message);
MessageBox.Show(message);
}
catch (DirectoryNotFoundException e)
{
message = "Unable to delete " + filePath + "\r\n";
message += String.Format("Reason: {0}", e.Message);
MessageBox.Show(message);
}
catch (Exception e)
{
message = "Unable to delete " + filePath + "\r\n";
message += String.Format("Reason: {0}", e.Message);
MessageBox.Show(message);
}
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Yes, that looks OK. Try it out and judge for yourself.
Paul Marfleet
"No, his mind is not for rent
To any God or government"
Tom Sawyer - Rush
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How can i fail my program so this works?
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Shani Aulakh wrote: How can i fail my program so this works?
What do you mean? Why would you want cause your program to deliberately fail?
Paul Marfleet
"No, his mind is not for rent
To any God or government"
Tom Sawyer - Rush
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Sorry for the confusing question. I meant to say, what should i do to see if it actually handle all exceptions
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If you want to produce a FileNoFoundException or DirectoryNotFoundException, just try doing something that involves a file/directory that doesn't exist.
Paul Marfleet
"No, his mind is not for rent
To any God or government"
Tom Sawyer - Rush
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If you just want to test that your catch blocks work the way you intend you can always throw an exception from code during testing. Just make sure to remove exception once you are convinced you're exception handling works the way you want. Depending on the application you could also use a driver for this.
throw new System.ApplicationException("Your message here");
You can replace ApplicationException with the exception types you actually want to test.
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How can I set characters limit in the ProperGrid control property. Like, a Name property is being diplayed inside the propertygrid. I don't want user to enter more than 5 characters in the Name field.
I know if i have to check the string lenght but how can i stop the user not exceed more than that
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netJP12L wrote: I don't want user to enter more than 5 characters in the Name field.
Why limit people to such few characters?
"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon
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i am trying to develop a player using mci...
i want to control volume with the track bar..... so what i did is
//
code//
mcisendstring(String.Format("set {0} volume to {1}",file, trackbar.value),String.Empty,0,0);
i don't see any effect
can someone help with this./..
another problem is getiing the length....
i don't know the format i am gettin my values in
what i do is
// first
mcisendstring("set file time format ms",String.Empty,0,0);
mcisendstring("status file length",result,255,0);
the result contains values which is unclear to me....
cud someone help with this as well?
thankx so much
//
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Not sure. Do you care to tell us a little more about mcisendstring?
"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon
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Paul Conrad wrote: mcisendstring?
mciendstring is a system call part of the MCI API(MULTIMEDIA CONTROL INTERFACE.... it takes a list of command strings to make these calls....
i get some help on it from the MSDN.. maybe more can be read there..
examples" mcisendstring("set CDAudio door open", Sring.Empty,0,0)"===
this will open a CD tray....
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My string is serial of words( abc& # SomeInterger; )
How can I convert it to utf8 as ( abc? )
Thanks!
QuynhTD
modified on Tuesday, December 18, 2007 1:44:31 PM
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"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon
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Hello everybody,
does anybody have any idea of how it's possible to access a specific TreeNode object in a TreeView, given the 'FullPath' property of that node ?
Thanks for helping,
Pat.
p.f. Goudjo-Ako
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