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A comment on Pointers Are Complicated, or What’s in a Byte?.

Re:Pointers Are Complicated, or What’s in a Byte? by miket94 on Wednesday July 25, 2018 @01:47PM (#17611218)
auto x = new int[8]; auto y = new int[8]; However, given how low-level a language C++ is, we can actually break this assumption by setting i to y-x. Since &x[i] is the same as x+i, this means we are actually writing 23 to &y[0].

This assumes that the address space of y starts at the end of the address space of x? In other words x+8==y? Could these two allocated blocks of memory ever not be continuous?

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Re:Pointers Are Complicated, or What’s in a Byte? by vardump on Wednesday July 25, 2018 @01:52PM (#17611264)
> However, given how low-level a language C++ is, we can actually break this assumption by setting i to y-x. Since &x[i] is the same as x+i, this means we are actually writing 23 to &y[0].

> This assumes that the address space of y starts at the end of the address space of x?

No it does not. Any value of x or y should "work", because y-x computes a difference between pointers.

> Could these two allocated blocks of memory ever not be continuous?

Probability they're not continuous is high and only gets higher as the heap gets more fragmented over time.

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