Visual-studio – Visual Studio: How to break on handled exceptions

debuggingexceptionvisual studio

I would like Visual Studio to break when a handled exception happens (i.e. I don't just want to see a "First chance" message, I want to debug the actual exception).

e.g. I want the debugger to break at the exception:

try
{
   System.IO.File.Delete(someFilename);
}
catch (Exception)
{
   //we really don't care at runtime if the file couldn't be deleted
}

I came across these notes for Visual Studio.NET:

1) In VS.NET go to the Debug Menu >>
"Exceptions…" >> "Common Language
Runtime Exceptions" >> "System" and
select "System.NullReferenceException"

2) In the bottom of that dialog there
is a "When the exception is thrown:"
group box, select "Break into the
debugger"

3) Run your scenario. When the
exception is thrown, the debugger will
stop and notify you with a dialog that
says something like:
"An exception of type "System.NullReferenceException" has
been thrown.
[Break] [Continue]"

Hit [Break]. This will put you on the
line of code that's causing the
problem.

But they do not apply to Visual Studio 2005 (there is no Exceptions option on the Debug menu).

Does anyone know where the find this options dialog in Visual Studio that the "When the exception is thrown" group box, with the option to "Break into the debugger"?

Update: The problem was that my Debug menu didn't have an Exceptions item. I customized the menu to manually add it.

Best Answer

With a solution open, go to the Debug - Exceptions (Ctrl+D,E) menu option. From there you can choose to break on Thrown or User-unhandled exceptions.

EDIT: My instance is set up with the C# "profile" perhaps it isn't there for other profiles?

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C# – Catch multiple exceptions at once

Catch System.Exception and switch on the types

catch (Exception ex)            
{                
    if (ex is FormatException || ex is OverflowException)
    {
        WebId = Guid.Empty;
        return;
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Python – How to safely create a nested directory in Python

On Python ≥ 3.5, use pathlib.Path.mkdir:

from pathlib import Path
Path("/my/directory").mkdir(parents=True, exist_ok=True)

For older versions of Python, I see two answers with good qualities, each with a small flaw, so I will give my take on it:

Try os.path.exists, and consider os.makedirs for the creation.

import os
if not os.path.exists(directory):
    os.makedirs(directory)

As noted in comments and elsewhere, there's a race condition – if the directory is created between the os.path.exists and the os.makedirs calls, the os.makedirs will fail with an OSError. Unfortunately, blanket-catching OSError and continuing is not foolproof, as it will ignore a failure to create the directory due to other factors, such as insufficient permissions, full disk, etc.

One option would be to trap the OSError and examine the embedded error code (see Is there a cross-platform way of getting information from Python’s OSError):

import os, errno

try:
    os.makedirs(directory)
except OSError as e:
    if e.errno != errno.EEXIST:
        raise

Alternatively, there could be a second os.path.exists, but suppose another created the directory after the first check, then removed it before the second one – we could still be fooled.

Depending on the application, the danger of concurrent operations may be more or less than the danger posed by other factors such as file permissions. The developer would have to know more about the particular application being developed and its expected environment before choosing an implementation.

Modern versions of Python improve this code quite a bit, both by exposing FileExistsError (in 3.3+)...

try:
    os.makedirs("path/to/directory")
except FileExistsError:
    # directory already exists
    pass

...and by allowing a keyword argument to os.makedirs called exist_ok (in 3.2+).

os.makedirs("path/to/directory", exist_ok=True)  # succeeds even if directory exists.

Best Answer

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C# – Catch multiple exceptions at once

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