Is it legal/well-defined C++ to call a non-static method that doesn’t access members through a null pointer?

by

This will probably work on most systems, but it is Undefined Behaviour. Quoth the Standard:

5.2.5.3

If E1 has the type “pointer to class X,” then the expression E1->E2 is converted to the equivalent form (*(E1)).E2 […]

And:

5.2.5.1

A postfix expression followed by a dot . or an arrow ->, optionally followed by the keyword template (14.8.1), and then followed by an id-expression, is a postfix expression. The postfix expression before the dot or arrow is evaluated;58) […]

58) This evaluation happens even if the result is unnecessary to determine the value of the entire postfix expression, for example if the id-expression denotes a static member.

Evaluation of *x where x is a null pointer results in Undefined Behaviour, so yours is clearly a case of UB, before the function is even entered.

More Related Contents:

  1. determine size of array if passed to function
  2. Is it good practice to NULL a pointer after deleting it?
  3. Testing pointers for validity (C/C++)
  4. NULL vs nullptr (Why was it replaced?) [duplicate]
  5. C++ standard: dereferencing NULL pointer to get a reference? [duplicate]
  6. C/C++ int[] vs int* (pointers vs. array notation). What is the difference?
  7. Checking if this is null
  8. Is there any reason to check for a NULL pointer before deleting?
  9. Can I use if (pointer) instead of if (pointer != NULL)?
  10. dereferencing the null pointer
  11. Why are NULL pointers defined differently in C and C++?
  12. Is it unspecified behavior to compare pointers to different arrays for equality?
  13. Do pointers to string literals remain valid after a function returns?
  14. why this unexpected variable change happens? [closed]
  15. Why should I use a pointer rather than the object itself?
  16. Are std::vector elements guaranteed to be contiguous?
  17. Is it safe to delete a NULL pointer?
  18. Correct way of declaring pointer variables in C/C++ [closed]
  19. Reason to Pass a Pointer by Reference in C++?
  20. Uses for multiple levels of pointer dereferences?
  21. Why dereferencing a null pointer is undefined behaviour?
  22. How to use an iterator?
  23. In either C or C++, should I check pointer parameters against NULL/nullptr?
  24. C++ correct way to return pointer to array from function
  25. Store an int in a char array?
  26. C++ typedef interpretation of const pointers
  27. Are non dereferenced iterators past the “one past-the-end” iterator of an array undefined behavior?
  28. Is there a null std::ostream implementation in C++ or libraries?
  29. int *array = new int[n]; what is this function actually doing?
  30. Is a Linked-List implementation without using pointers possible or not?

Leave a Comment