From: ulrich.eckhardt@dominolaser.com   
      
   Am 07.11.2011 21:02, schrieb Carlos Moreno:   
   > So, the issue: I'm trying to convince a colleague of mine that   
   > using recursion in a tree structure, and allowing it to step outside   
   > the tree by calling the method on the NULL pointers is not legal   
   > (as in, it invokes undefined behaviour).   
   >   
   > The thing is, it's proving to be an "uphill battle", in that the   
   > solution, legal or not, simply happens to work (quite likely works   
   > on every compiler that has ever existed --- at least every "real"   
   > compiler, as opposed to academic/proof-of-concept compilers),   
   > and it simplifies the code a bit.   
      
   Just make the function virtual and watch it break. ;)   
      
   That said, there is at least one compiler out there that (implicitly)   
   guarantees that you can call non-virtual functions on null pointers, and   
   that is MSVC (and probably Intel's in MSVC-compat-mode). MS use this in   
   their MFC class library (e.g. CWnd::GetSafeHWND()).   
      
   Uli   
      
      
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