Question

How to correctly let an exception to bubble up?
If I use Try-Catch when calling a method, is just throwing an exception inside a method like not trying to catch it at all?
For illustration: Are these approaches do the same work?

Example 1:

try
{
   MyFileHandlingMethod();             
}
catch (IOException ex)
{
   string recfilepath = "...";
   string rectoadd = "RecDateTime=" + DateTime.Now.ToString()+ ...+ex.Message.ToString();
   File.AppendAllText(recfilepath, rectoadd);
}
catch (exception)
{
   throw;
}
...
MyFileHandlingMethod()
{
   ...
   TextReader tr2 = new StreamReader(nfilepath);
   resultN = tr2.ReadLine();
   tr2.Close();  
   ...
}

Example 2:

try
{
   MyFileHandlingMethod();             
}
catch (IOException ex)
{
   string recfilepath = "...";
   string rectoadd = "RecDateTime=" + DateTime.Now.ToString()+ ...+ex.Message.ToString();
   File.AppendAllText(recfilepath, rectoadd);
}
catch (exception)
{
   throw;
}
...
MyFileHandlingMethod()
{
   ...
     try
     {
        TextReader tr2 = new StreamReader(nfilepath);
        resultN = tr2.ReadLine();
        tr2.Close();              
     }
     catch (Exception)
     {
        throw;     
     }       
   ...
}

Answer 1

Yes, those 2 approaches have almost the same effect; rethrowing will unwind the stack of the exception – meaning the stack frames “below” the method where the throw; will be discarded. They’ll still be in the stack trace, but you won’t be able to access their local variables in the debugger unless you break on thrown exceptions.

A catch/throw block like the one below where you don’t do anything with the exception (like logging), is useless:

 catch (Exception)
 {
    throw;     
 } 

Remove it to clean up, in both your samples. In general, avoid entering a catch block if possible

---

And your method has another exception related problem, it does not free resources properly. The tr2.Close(); belongs in a finally clause but it’s much easier to let the compiler handle that with a using() {} block :

void MyFileHandlingMethod()
{
   ...
   using (TextReader tr2 = new StreamReader(nfilepath))
   {
     resultN = tr2.ReadLine();         
   } //tr2.Dispose() inserted automatically here        
   ...
}