Sorry Tim, but I'm afraid we just can't help if we can't reproduce the scenario
that you are running yourself into.  Any number of things could be going
wrong in this scenario and the Interpreter code is sufficiently complex that
I'm not sure anyone could poke a guess at why the exception is occuring.

Eat the cost of turning your debugging on for a few days and give us the
string that is tossing the exception.

 hi,
 posting this a third time in the hope that someone may explain why it happens, or that MS will acknowledge a bug and fix it in 2.0...

 i have a regular expression and very occassionally i'm getting an index out
 of bounds exception from one of the inner framework methods, when i use
 Match().  i don't know what the input is because its in a production
 environment and all debugging is turned off.

 my code is as follows:
 ----------------------------
 Regex rex = new Regex(@"http\:\/\/([a-zA-z0-9\-]*\.?)*?(\:[0-9]*)??\/",
 RegexOptions.IgnoreCase);
 Match match = rex.Match(absoluteUrl);        // exception happens here
 if(match.Success)
    return "/" + absoluteUrl.Replace(match.ToString(), ""); // strip out the
 absolute part of the entire url, returning the relative url.
 -------------------------------

 >
 > stack trace:
 > -------------------------------
 > IndexOutOfRangeException at
 > System.Text.RegularExpressions.RegexInterpreter.Go() at
 > System.Text.RegularExpressions.RegexRunner.Scan(Regex regex, String text,
 > Int32 textbeg, Int32 textend, Int32 textstart, Int32 prevlen, Boolean
 quick)
 > at
 > System.Text.RegularExpressions.Regex.Run(Boolean quick, Int32 prevlen,
 > String input, Int32 beginning, Int32 length, Int32 startat) at
 > System.Text.RegularExpressions.Regex.Match(String input)
 > -------------------------------
 >
 > thanks for any help
 > tim mackey.

 \\ email: tim at mackey dot ie //
 \\ blog: http://tim.mackey.ie //
 67d0ebfec70e8db3

Tim,
Have you considered calling Microsoft directly with the problem? If there is
an actual bug you will not be charged with the support call.

Have you considered asking in a different newsgroup?
microsoft.public.dotnet.framework or microsoft.public.dotnet.general have a
larger following someone in one of those may have come across your
problem...

As Justin suggested, have you considered putting the RegEx.Match in a try
catch & writing out the URL that is causing problems? So as to identify the
URL that is causing an issue...

I would consider creating a custom exception class so as to log the URL &
other context info that is causing the exception...

try
{
   Match match = rex.Match(absoluteUrl);        // exception happens here
}
catch (Exception ex)
{
   // throw new exception with the input, pattern & innerException
   throw new MyMatchException(absoluteUrl, pattern, ex);
}
if(match.Success)
  return "/" + absoluteUrl.Replace(match.ToString(), ""); // strip out the

Note for production environments I find it invaluable to add global
exception handlers to my application, where the global exception handler
logs Exception.ToString to the EventLog. With a custom exception class, the
log would contain the URL & other context info that caused the problem. The
Exception Management Block is useful for this logging & provides options as
to how & where things are logged...

http://msdn.microsoft.com/webservices/building/frameworkandstudio/default.aspx?p
ull=/library/en-us/dnbda/html/emab-rm.asp

Depending on the type of application you are creating, .NET has three
different global exception handlers.

For ASP.NET look at:
   System.Web.HttpApplication.Error event
   Normally placed in your Global.asax file.

For console applications look at:
   System.AppDomain.UnhandledException event
   Use AddHandler in your Sub Main.

For Windows Forms look at:
   System.Windows.Forms.Application.ThreadException event
   Use AddHandler in your Sub Main.

It can be beneficial to combine the above global handlers in your app, as
well as wrap your Sub Main in a try catch itself.

There is an article in the June 2004 MSDN Magazine that shows how to
implement the global exception handling in .NET that explains why & when you
use multiple of the above handlers...

http://msdn.microsoft.com/msdnmag/issues/04/06/NET/default.aspx

For example: In my Windows Forms apps I would have a handler attached to the
Application.ThreadException event, plus a Try/Catch in my Main. The
Try/Catch in Main only catches exceptions if the constructor of the MainForm
raises an exception, the Application.ThreadException handler will catch all
uncaught exceptions from any form/control event handlers.

Hope this helps
Jay

Hope this helps
Jay

hi,
posting this a third time in the hope that someone may explain why it
happens, or that MS will acknowledge a bug and fix it in 2.0...

i have a regular expression and very occassionally i'm getting an index out
of bounds exception from one of the inner framework methods, when i use
Match().  i don't know what the input is because its in a production
environment and all debugging is turned off.

my code is as follows:
----------------------------
Regex rex = new Regex(@"http\:\/\/([a-zA-z0-9\-]*\.?)*?(\:[0-9]*)??\/",
RegexOptions.IgnoreCase);
Match match = rex.Match(absoluteUrl);        // exception happens here
if(match.Success)
  return "/" + absoluteUrl.Replace(match.ToString(), ""); // strip out the
absolute part of the entire url, returning the relative url.
-------------------------------

quick)

\\ email: tim at mackey dot ie //
\\ blog: http://tim.mackey.ie //
67d0ebfec70e8db3

have you considered the possibility that certain URLs might be of the form:
http://www.somesite.com/something.aspx?site=http://somesitereference.com - in this case, your regex is probably matching the second string and then when you run the Replace command your getting a out of range coz it exceeds the string length.

You could add a condition to check if the index recieved from the regex match is out of bounds (less than zero or greater than the string length, or if the string is empty). In any of these cases, you could log the URL for inspection later like other people have suggested already.

Regards
Pandurang

In order to verify that it's a bug, we would probably need a copy of the
url string that produces the exception as well.

You need to turn on some kind of logging so that you get hold of the value.

Tim, I did some experimenting with your code snippet and found that an
absolute url without the trailing / will cause this exception.  For
example: "http://www.msn.com".  I'll enter a bug to track this and it
should get fixed in the next version.  Thanks for letting us know about
this!

David