Checking for NULL pointer in C/C++ [closed]

by

In my experience, tests of the form if (ptr) or if (!ptr) are preferred. They do not depend on the definition of the symbol NULL. They do not expose the opportunity for the accidental assignment. And they are clear and succinct.

Edit: As SoapBox points out in a comment, they are compatible with C++ classes such as auto_ptr that are objects that act as pointers and which provide a conversion to bool to enable exactly this idiom. For these objects, an explicit comparison to NULL would have to invoke a conversion to pointer which may have other semantic side effects or be more expensive than the simple existence check that the bool conversion implies.

I have a preference for code that says what it means without unneeded text. if (ptr != NULL) has the same meaning as if (ptr) but at the cost of redundant specificity. The next logical thing is to write if ((ptr != NULL) == TRUE) and that way lies madness. The C language is clear that a boolean tested by if, while or the like has a specific meaning of non-zero value is true and zero is false. Redundancy does not make it clearer.

More Related Contents:

  1. Can I use if (pointer) instead of if (pointer != NULL)?
  2. #ifdef vs #if – which is better/safer as a method for enabling/disabling compilation of particular sections of code?
  3. For loop with pointers and a terminating null
  4. c++ if specific words from string
  5. return statement vs exit() in main()
  6. What open source C++ static analysis tools are available? [closed]
  7. Correct way of declaring pointer variables in C/C++ [closed]
  8. What is the difference between these (bCondition == NULL) and (NULL==bCondition)?
  9. Is calling destructor manually always a sign of bad design?
  10. Difference between “if constexpr()” Vs “if()”
  11. A free tool to check C/C++ source code against a set of coding standards? [closed]
  12. What are the advantages of using nullptr?
  13. Variable assignment in an “if” condition
  14. In either C or C++, should I check pointer parameters against NULL/nullptr?
  15. How to avoid “if” chains?
  16. How to check for equals? (0 == i) or (i == 0) [closed]
  17. When should you use the “this” keyword in C++? [duplicate]
  18. Iterate through a C++ Vector using a ‘for’ loop
  19. How does switch compile in Visual C++ and how optimized and fast is it?
  20. What are your favorite C++ Coding Style idioms [closed]
  21. Unique ways to use the null coalescing operator [closed]
  22. How can I avoid including class implementation files?
  23. Why does this if condition fail for comparison of negative and positive integers [duplicate]
  24. At what point does dereferencing the null pointer become undefined behavior?
  25. Default parameters with C++ constructors [closed]
  26. comma operator in if condition
  27. if statement not working right?
  28. Do I need to put constexpr after else-if?
  29. c++ standard practice: virtual interface classes vs. templates
  30. if / else at compile time in C++?

Leave a Comment