find exception type

Question

I have created custom exception class

public class Web2PDFException : Exception
{


    public Web2PDFException(string message,
       Exception innerException)
        : base(message, innerException)
    {
    }
}

in my application I want to find out is throw exception is my custom exception or not.

try
{
}
catch (Exception err)
{
//Find exception type here
}

Answer 1

either

try
{
}
catch ( Web2PDFException ex )
{
}

or (if you need to write a general handler - which is generally a bad idea, but if you're sure it's best for you, you're sure):

 if( err is Web2PDFException)
 {
 }

or (in certain cases if you need to do some more complex type hierarchy stuff that cant be expressed with is)

 if( err.GetType().IsAssignableFrom(typeof(Web2PDFException)))
 {
 }

or switch to VB.NET and use is or Type.IsAssignableFrom in Exception Filters

Answer 2

try
{
    // Some code
}
catch (Web2PDFException ex)
{
    // It's your special exception
}
catch (Exception ex)
{
    // Any other exception here
}

Answer 3

You should always catch exceptions as concrete as possible, so you should use

try
{
    //code
}
catch (Web2PDFException ex)
{
    //Handle the exception here
}

You chould of course use something like this if you insist:

try
{
}
catch (Exception err)
{
    if (err is Web2PDFException)
    {
        //Code
    }
}

Answer 4

try
{
}
catch (Exception err)
{
    if (err is Web2PDFException)
        DoWhatever();
}

but there is probably a better way of doing whatever it is you want.

Answer 5

you can add some extra information to your exception in your class and then when you catch the exception you can control your custom information to identify your exception

this.Data["mykey"]="keyvalue"; //you can add any type of data if you want

and then you can get your value

string mystr = (string) err.Data["mykey"];

like that for more information: http://msdn.microsoft.com/en-us/library/system.exception.data.aspx