Eiffel "Gotchas"

07 April 1998

Gotcha #5 - null pointers

Suppose you wish to test that a pointer is not null before passing it to an external routine. On some Eiffel compilers, the following code will compile and run, but it won't work as expected. What's wrong?

   p: POINTER
   ...
   if p = void then
      print("Nil pointer.%N")
   else
      some_external_routine(p)
   end

ANSWER

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Eiffel "Gotchas"