C# using an exception for flow control

Question

I have some text in a string which I'm reading in. The object which contains the string provides a method for me to extract the contents of the string and then throws an exception (EndOfStreamException) when the string is empty. At that point I'd like to finish my data extraction and continue with working on it. I'm not very certain how to do this. Here is what I am guessing.

while(/*some condition on the data*/)
try
{
    objWithString.ExtractData();
}
catch (Exception e)
{
    if(e is EndOfStreamException)
        {
            break;
        }
    else
       throw e;
}
}

You can just catch(EndOfStreamException e) instead of using the if block — smartcaveman
– smartcaveman, Commented Nov 29, 2011 at 5:06
I know, I didn't write this code and I'd never seen such code but it works. It's a small project. — s5s
– s5s, Commented Nov 29, 2011 at 5:10
See, if the objWithString has other methods. May be one of them may help you without throwing an exception. If it's some normal third party library, I'm sure there is a such functionality — Kamarey
– Kamarey, Commented Nov 29, 2011 at 5:13

EMP · Accepted Answer · 2011-11-29 05:06:04Z

4

That will work, but it would be better to catch the specific exception than to do the test at runtime, ie.

while (/*some condition on the data*/)
try
{
    objWithString.ExtractData();
}
catch (EndOfStreamException)
{
    break;
}

I'm not entirely sure if "break" will work inside a catch clause. If not, you may have to extract this into a method and use "return".

Generally using exceptions for flow control is considered poor design, since exceptions are intended for "exceptional" conditions and reaching the end of the stream is normal and expected, not exceptional. Of course, if you have no control over the implementation of the stream then you have to go with this approach.

answered Nov 29, 2011 at 5:06

EMP

62.6k57 gold badges168 silver badges223 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Dan Bryant Over a year ago

Throwing and catching an exception is also quite expensive, performance-wise. This is another good reason why exceptions should not generally be thrown during the typical use case of a method.

Collectives™ on Stack Overflow

C# using an exception for flow control

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related