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I want to perform check for memory alignment of some type T . The straightforward way to do this is if (((uintptr_t)&var & __alignof(T) - 1) == 0) ... however, uintptr_t is not part of existing C++ standard and it is not supported by some compilers, so I'm looking for a portable alternative way to do this and std::ptrdiff_t looks good for me. std::ptrdiff_t guaranteed to be able to store difference between two pointers, but who says that one of those pointers cannot be null pointer? In that case std::ptrdiff_t has to be at least same size as the pointer itself. template <typename T> bool is_properly_aligned(const T* const ptr) { std::ptrdiff_t diff = (ptr - static_cast<T*>(0)) * sizeof(T); return ((diff & __alignof(T) - 1) == 0); } or like that (to get rid of multiplication by sizeof(T) ) template <typename T> bool is_properly_aligned(const T* const ptr) { std::ptrdiff_t diff = reinterpret_cast<const char*>(ptr) - static_cast<const char*>(0); return ((diff & __alignof(T) - 1) == 0); } What do you think about such kind of solution? Is it portable enough? I don't see any reasons why this should fail, however I would like to confirm. Thanks.

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