alignof

What's the difference between sizeof and alignof? #include <iostream> #define SIZEOF_ALIGNOF(T) std::cout<< sizeof(T) << '/' << alignof(T) << std::endl int main(int, char**) { SIZEOF_ALIGNOF(unsigned char); SIZEOF_ALIGNOF(char); SIZEOF_ALIGNOF(unsigned short int); SIZEOF_ALIGNOF(short int); SIZEOF_ALIGNOF(unsigned int); SIZEOF_ALIGNOF(int); SIZEOF_ALIGNOF(float); SIZEOF_ALIGNOF(unsigned long int); SIZEOF_ALIGNOF(long int); SIZEOF_ALIGNOF(unsigned long long int); SIZEOF_ALIGNOF(long long int); SIZEOF_ALIGNOF(double); } will output 1/1 1/1 2/2 2/2 4/4 4/4 4/4 4/4 4/4 8/8 8/8 8/8 I think I don't

For any object type T is it always the case that sizeof(T) is at least as large as alignof(T) ? Intuitively it seems so, since even when you adjust the alignment of objects like: struct small { char c; }; above what it would normally be, their "size" is also adjusted upwards so that the relationship between objects in an array makes sense while maintaining alignment (at least in my testing . For example: struct alignas(16) small16 { char c; }; Has both a size and alignment of 16. At least in standard C++, for anything you can make an array of (with length > 1), this will have to be true. If