C#: multiple catch clauses

Question

Consider the following:

try { 
    FileStream fileStream = new FileStream("C:\files\file1.txt", FileMode.Append); }
catch (DirectoryNotFoundException e) 
    { MessageBox.Show("Directory not found. " + e.Message); }
catch (IOException e) 
    { MessageBox.Show("Other IO Error. " + e.Message); }
catch (Exception e) 
    { MessageBox.Show("Other Error. " + e.Message); }

Will a DirectoryNotFoundException exception get handled by all three catch clauses or just the first one?

Answer 1

Just the first one. The exception doesn't propagate to all matching catch clauses.

From the C# 4 spec, section 8.9.5:

The first catch clauses that specifies the exception type or a base type of the exception type is considered a match. [...] If a matching catch clause is located, the exception propagation is completed by transferring control to the block of that catch clause.

Here the "completed" part indicates that after control has been transferred, that's the end of the special handling, effectively.