C++ find highest element in array that isant a particular value

Question

I am using some data that uses some an extremely high value as an error code. I am currently using std max element, is there a way to do this ignoring a particular value?. eg max element that isant a particular number.

why isn't scanning from start to finish and finding the max ok? — Catalyst
– Catalyst, Commented Aug 20, 2014 at 15:10
Because there is a value in the dataset that is an error code for something else that I would like to ignore for this calculation. — user3512203
– user3512203, Commented Aug 20, 2014 at 15:11
e.g find max but ignore all values of 55505. Obviously I can iterate just wondering if there is an simple method considering its only one value. — user3512203
– user3512203, Commented Aug 20, 2014 at 15:12
Use std::max_element with a (lambda) function comp to tell if a value is bigger than another. Implement it, such that e.g. 55505 is the smallest element. — tgmath
– tgmath, Commented Aug 20, 2014 at 15:14

Bill Lynch · Accepted Answer · 2014-08-20 15:14:25Z

5

So, let's use a custom comparator as part of the call to std::max_element. We'll just make sure that if we see the error code, then we'll make that smaller than all other elements.

auto maxElement = std::max_element(std::begin(container), std::end(container), [](T const & lhs, T const & rhs) -> bool {
    if (rhs == error_code)
         return false;
    if (lhs == error_code)
         return true;
    return lhs < rhs;
}

answered Aug 20, 2014 at 15:14

Bill Lynch

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2 Comments

Jarod42 Over a year ago

I would move rhs test first to satisfy (t < t) == false.

Bill Lynch Over a year ago

@Jarod42: I was thinking about if we'd need a case for lhs == rhs == error_code but that should cover it as well. Good idea.

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