Long ago I internalized the point that sizeof() does
not return the minimum number of bytes that need to
be copied in an aggregate assignment but rather the
spacing between elements in an array:
struct foo { ... };
foo a[2];
((char*)&a[0]) + sizeof(foo) equals ((char*)&a[1])
This is a bit of a hole in the language definition
since there really is no way to obtain that minimum
number. Hence using sizeof() as the length of a
memcpy() to set a freestanding risks trashing some
other object if the compiler has practiced any kind
storage packing.
/john
