Segmentation fault trying to dereference an iterator

Question

I'm trying to find the maximum value of a vector using std::max_element. When I run the program I get a segmentation fault that I believe is to do with std::end going over the end of the vector? I've tried changing it to std::end(tempdata)-1) but to no avail.

    auto max = std::max_element(std::begin(tempdata), std::end(tempdata));
    std::ofstream maxcurrent("maxcurrent.txt", std::ios::app);
    maxcurrent << v << std::setw(15) << *max << std::endl;

Having looked at this answer I don't see why mine isn't working.

Which line segfaults? The `std::max_element()` invocation (as the question's text suggests) or the `*max` dereference (as the question's title suggests)? And is `tempdata` nonempty? — Angew is no longer proud of SO, Jan 15 '14 at 12:31

score 5 · Accepted Answer · answered Jan 15 '14 at 12:31

5

It won't work when max is std::end(tempdata) which can occurs if your tempdata is empty.

Iterator to the greatest element in the range [first, last). If several elements in the range are equivalent to the greatest element, returns the iterator to the first such element. Returns last if the range is empty.

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answered Jan 15 '14 at 12:31

Johan

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I found that data wasn't getting written to tempdata properly, it's fixed now. Thank you. – oxidising Jan 15 '14 at 12:38

Segmentation fault trying to dereference an iterator

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