undefined | Better HN

0 pointsmatheusmoreira2y ago0 comments

Are memory blocks collections though? An empty list or table makes intuitive sense. Does a zero sized memory block make sense? I'm having trouble understanding that. If the memory has size zero, then by definition there is nothing to point to, nothing whose address can be taken.

I definitely see the benefits of well-defined arithmetic on null pointers. As a data type though it seems to me that any pointer could be a zero sized allocation.

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anderskaseorg2y ago

When you allocate memory for an empty array with malloc(num * size) where num == 0, you get a zero-sized memory block. As discussed in the article, representing this with a null pointer causes problems, because that results in undefined behavior in memcpy (despite asking it to copy 0 bytes). So we want it to be a real memory block that can be safely passed to free().

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0 pointsmatheusmoreira2y ago0 comments

I definitely see the benefits of well-defined arithmetic on null pointers. As a data type though it seems to me that any pointer could be a zero sized allocation.

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anderskaseorg2y ago

j / k navigate · click thread line to collapse