Why can I call max_element without "std::" and without "using namespace std"?

Asked Nov 29 '17 at 14:36

Active Nov 29 '17 at 14:40

Viewed 107 times

Consider the following code:

#include <algorithm>

int main() {
        std::vector<int> v = {1,2,3};
        max_element(v.begin(), v.end());
        return 0;
}

This compiles fine with gcc 7.2.0 and clang++ 3.9.1. I'd expect that I need to write std::max_element, but it seems that at least some functions in <algorithm> are in the global namespace - opposed to the draft of the C++17 standard, which shows the functions living in namespace std.

What is going on here?

edited Nov 29 '17 at 14:40

Jarod42

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asked Nov 29 '17 at 14:36

Philipp Ludwig

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`std` is deduced from the arguments, who's types belong to `std`. See http://en.cppreference.com/w/cpp/language/adl – François Andrieux Nov 29 '17 at 14:37
@FrançoisAndrieux: you should post answers as answers, not comments. – You Nov 29 '17 at 14:38
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Btw `std::vector::iterator` might simply be `int*` and so ADL won't apply and `std::` would be required. – Jarod42 Nov 29 '17 at 14:41
@FrançoisAndrieux Thanks for the explanation! – Philipp Ludwig Nov 30 '17 at 08:19

Why can I call max_element without "std::" and without "using namespace std"?

0 Answers0