Why do private member variables behaved like protected in the same module when creating deriving class?
schveiguy at gmail.com
Thu Nov 1 20:27:16 UTC 2018
On 11/1/18 4:15 PM, Paul Backus wrote:
> On Thursday, 1 November 2018 at 19:26:05 UTC, Steven Schveighoffer wrote:
>> My testing looks like it's the same:
>> #include <stdio.h>
>> int main()
>> int arr;
>> int *ptr = arr + 1; // point at second element so we can do
>> negative indexing legally
>> int idx1 = 0;
>> ptr[--idx1] = 5;
>> printf("%d\n", arr); // 5
>> size_t idx2 = 0;
>> ptr[--idx2] = 6;
>> printf("%d\n", arr); // 6
>> return 0;
> `ptr[--idx2]` is undefined behavior (out-of-bounds array access), so the
> fact that it works that way is just a coincidence.
Either way, I don't see it causing a segfault -- the purported benefit.
But maybe on Patrick's actual arch it did. In any case, undefined
behavior is bad whether you do it with an int or size_t :)
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