Is it safe to memset bool to 0?

by

Is it guaranteed by the law? No.

C++ says nothing about the representation of bool values.

Is it guaranteed by practical reality? Yes.

I mean, if you wish to find a C++ implementation that does not represent boolean false as a sequence of zeroes, I shall wish you luck. Given that false must implicitly convert to 0, and true must implicitly convert to 1, and 0 must implicitly convert to false, and non-0 must implicitly convert to true … well, you’d be silly to implement it any other way.

Whether that means it’s “safe” is for you to decide.

I don’t usually say this, but if I were in your situation I would be happy to let this slide. If you’re really concerned, you can add a test executable to your distributable to validate the precondition on each target platform before installing the real project.

More Related Contents:

  1. Order of evaluation of arguments using std::cout
  2. Take the address of a one-past-the-end array element via subscript: legal by the C++ Standard or not?
  3. Do I need to cast to unsigned char before calling toupper(), tolower(), et al.?
  4. Do distinct functions have distinct addresses?
  5. Is the size of std::array defined by standard
  6. Why class data members can’t be initialized by direct initialization syntax?
  7. Is adding to a “char *” pointer UB, when it doesn’t actually point to a char array?
  8. Efficient unsigned-to-signed cast avoiding implementation-defined behavior
  9. Is a pointer with the right address and type still always a valid pointer since C++17?
  10. Floating point comparison revisited
  11. Does not evaluating the expression to which sizeof is applied make it legal to dereference a null or invalid pointer inside sizeof in C++?
  12. In C++11, does `i += ++i + 1` exhibit undefined behavior?
  13. Pure virtual functions may not have an inline definition. Why?
  14. What does the void() in decltype(void()) mean exactly?
  15. Are non dereferenced iterators past the “one past-the-end” iterator of an array undefined behavior?
  16. Can the point-of-instantiation be delayed until the end of the translation unit?
  17. When instantiating a template, should members of its incomplete argument types be visible?
  18. Is most vexing parse a formally defined concept
  19. Pseudo-destructor call does not destroy an object
  20. Why is a constexpr function on a reference not constexpr?
  21. Will consteval functions allow template parameters dependent on function arguments?
  22. How can an incomplete type be used as a template parameter to vector here?
  23. Is the Empty Base Class Optimization now a mandatory optimization (at least for standard-layout classes)?
  24. Classes with both template and non-template conversion operators in the condition of switch statement
  25. Is it allowed for a compiler to optimize away a local volatile variable?
  26. reinterpret_cast between char* and std::uint8_t* – safe?
  27. What is the difference between std::quick_exit and std::abort and why was std::quick_exit needed?
  28. Why is `make_unique` disallowed?
  29. Using std::bind with member function, use object pointer or not for this argument?
  30. Why don’t I need to specify “typename” before a dependent type in C++20?

Leave a Comment