Why is try {...} finally {...} good; try {...} catch{} bad?

c# .net exception-handling try-catch try-catch-finally
mbeckish picture mbeckish · Sep 24, 2008 · Viewed 89.1k times · Source

I have seen people say that it is bad form to use catch with no arguments, especially if that catch doesn't do anything:

StreamReader reader=new  StreamReader("myfile.txt");
try
{
  int i = 5 / 0;
}
catch   // No args, so it will catch any exception
{}
reader.Close();

However, this is considered good form:

StreamReader reader=new  StreamReader("myfile.txt");
try
{
  int i = 5 / 0;
}
finally   // Will execute despite any exception
{
  reader.Close();
}

As far as I can tell, the only difference between putting cleanup code in a finally block and putting cleanup code after the try..catch blocks is if you have return statements in your try block (in that case, the cleanup code in finally will run, but code after the try..catch will not).

Otherwise, what's so special about finally?

Answer

Khoth picture Khoth · Sep 24, 2008

The big difference is that try...catch will swallow the exception, hiding the fact that an error occurred. try..finally will run your cleanup code and then the exception will keep going, to be handled by something that knows what to do with it.

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