CODEWITHSUNDEEP
c#try-catch
broadband
broadband

Reputation: 3488

Finally block executing before catch

As far as I understand try-catch-finally statement, just after exception is caught finally block gets executed. How does this apply when function throws exception, like example below. What if some resources are released in finally block which by initial exception could not be. Does this mean that finally block throws new (another) exception, overriding original exception.

I know that you can catch the exception that might be thrown in the try block of a try-finally statement higher up the call stack. That is, you can catch the exception in the method that calls the method that contains the try-finally statement (msdn documentation).

static void foo()   
{
  try   
  {
    Console.WriteLine("foo");
    throw new Exception("exception");   
  }   
  finally   
  {
    Console.WriteLine("foo's finally called");   
  }   
}

static void Main(string[] args)
{
  try
  {
    foo();
  }
  catch (Exception e)
  {
    Console.WriteLine("Exception caught");
  }
}

Output:

foo
foo's finally called
Exception caught

Upvotes: 6

Views: 7936

Answers (3)

bolt19
bolt19

Reputation: 2053

this is basically what you are trying to do:

 static void Main(string[] args)
 {
   try
   {
       try   
       {
          Console.WriteLine("foo");
          throw new Exception("exception");   //error occurs here
       }   
       finally   //will execute this as it is the first exception statement
       {
           Console.WriteLine("foo's finally called");   
       }   
    }
    catch (Exception e)  // then this
    {
       Console.WriteLine("Exception caught");
    }
 }

I should also add that the code in the finally block is executed no matter what happens in the try and catch blocks

Upvotes: 2

DDave
DDave

Reputation: 618

When you are using try-catch-finally. If your code get any error then it goes to first catch and then finally. If your code does not threw any error then it will at last calls the finally and then further goes for execution.

this explains with good example.

Upvotes: 1

Jon
Jon

Reputation: 437336

As far as I understand try-catch-finally statement, just after exception is caught finally block gets executed.

No, that's wrong.

The finally block gets executed after either an applicable catch clause block has been executed, or immediately after the exception is thrown if no applicable catch exists. However, that only applies to catch and finally on the same try block -- if the exception is propagated, finally will run before any catch and/or finally that is further up the call stack.

How does this apply when function throws exception, like example below.

foo is called, it throws, and its finally block is executed. Since there was no catch the exception propagates and is caught inside main.

What if some resources are released in finally block which by initial exception could not be.

I do not understand the question.

Does this mean that finally block throws new (another) exception, overriding original exception.

Yes, that's how it works.

Upvotes: 11

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