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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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().