>>> [...], using the C standard guaranteed property that the address of >>> the first member is the address of the structure, allowing to cast >>> pointers in order to operate whether on the base structure or on >>> the derived structure? >> Which standard promises this, and what exactly does it promise? > K & R, "The C Programming Language", second edition (english > version), p 213:
> If a > pointer to a structure is cast to the type of a pointer to its > first member, the result refers to the first member. ! Curious. I would expect the standards to preserve that promise, yes, but I haven't yet found anything equivalent in C99. I've been searching for things like "first (element|member)" with no success. But this is not quite what you said (though admittedly "address" is fuzzy enough it's not clear); the cast may involve significant changes (for example, the resulting pointer may be larger than the original; I *think* it might even be smaller, though I'm not sure - very little is promised about pointer sizes). Also, is there anything promising that casting back, that casting a pointer to the type of the first element, which actually points to such a first element, to a pointer to the containing struct type, returns a pointer which points to that containing struct? /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
