From: ike@ukato.freeshell.org   
      
   On 2013-07-20, kawninzx6@googlemail.com  wrote:   
   > class BaseFoo   
   > {   
   >   public:   
   >     virtual ~BaseFoo() {}   
   > };   
   >   
   > class Foo : public BaseFoo {};   
   >   
   > void process(int& i) { ... }   
   >   
   > void process(Foo& foo) { ... }   
   >   
   > BaseFoo* getFoo() { ... }   
   >   
   > int main()   
   > {   
   >   int *i = NULL;   
   >   void process(*i); // (1)   
   >   
   >   try   
   >   {   
   >     process(dynamic_cast(*getFoo())); // (2)   
   >   }   
   >   catch (const std::exception&)   
   >   {   
   >     // ignore bad_cast exception   
   >   }   
   >   
   >   return 0;   
   > }   
   >   
   > (1) - This is always undefined behavior, right?   
      
   Yes, dereferencing a null pointer produces undefined behaviour.   
      
   > (2) - Does this dynamic_cast produce undefined behavior if   
   >       getFoo() returns a NULL pointer?   
      
   It's not the dynamic_cast that produces undefined behaviour,   
   it's the dereference of the null pointer returned by getFoo().   
      
      
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