Alex Rivera | Logout

Catch multiple exceptions at once?

Asked 2008-09-25T20:56:08.513
2634

It is discouraged to catch System.Exception errors. Instead, only the "known" exceptions should be caught.

This sometimes leads to unnecessary repetitive code, for example:

try
{
    WebId = new Guid(queryString["web"]);
}
catch (FormatException)
{
    WebId = Guid.Empty;
}
catch (OverflowException)
{
    WebId = Guid.Empty;
}

Is there a way to catch both exceptions and only set WebId = Guid.Empty once?

The given example is rather simple, as it's only a GUID, but imagine code where you modify an object multiple times, and if one of the manipulations fails as expected, you want to "reset" the object. However, if there is an unexpected exception, I still want to throw that higher.

c# .net exception
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2 Answers

2493

Catch System.Exception and switch on the types

catch (Exception ex)            
{                
    if (ex is FormatException || ex is OverflowException)
    {
        WebId = Guid.Empty;
    }
    else
        throw;
}
answered 2008-09-25T21:01:49.530
204

Not in C# unfortunately, as you'd need an exception filter to do it and C# doesn't expose that feature of MSIL. VB.NET does have this capability though, e.g.

Catch ex As Exception When TypeOf ex Is FormatException OrElse TypeOf ex Is OverflowException

What you could do is use an anonymous function to encapsulate your on-error code, and then call it in those specific catch blocks:

Action onError = () => WebId = Guid.Empty;
try
{
    // something
}
catch (FormatException)
{
    onError();
}
catch (OverflowException)
{
    onError();
}
answered 2008-09-25T21:03:57.840

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