c++ template ambiguous error

Question

Here's my code trying to simply add 2 numbers.

#include <iostream>
#include <string>
using namespace std;

template<class first, class second>
first plus(first x, second y) {

    return x + y;
}
int main() {

    int a = 123;
    int b = 21;

    plus(a, b);

    return 0;
}

The plus() gives me an error stating that it's "ambiguous". This is basically copied code I've seen in tutorials(where it has worked!) on templates so I'm really confused now.

Try to remove `using namespace std;` or call it like this: `::plus(a, b);` or wrap it inside a namespace. — DimChtz, Jul 27 '17 at 23:07
I suspect that it has to do with `using namespace std` and the fact that there is a [`std::plus`](http://en.cppreference.com/w/cpp/utility/functional/plus) — HeroicKatora, Jul 27 '17 at 23:08
I hope you learned that `using namespace std;` is a bad practice. — drescherjm, Jul 27 '17 at 23:09
also the fact std::plus exist so changing the function name also works.. — SS2, Jul 27 '17 at 23:10
https://stackoverflow.com/questions/1452721/why-is-using-namespace-std-considered-bad-practice — drescherjm, Jul 27 '17 at 23:11
@SS2, or, namespaces are a honking good idea, let's do more of those. IE, don't drag everything from another namespace into the current one. — Alex Huszagh, Jul 27 '17 at 23:13

score 2 · Answer 1 · answered Jul 27 '17 at 23:07

2

Remove the using namespace std, you are colliding with std::plus

http://en.cppreference.com/w/cpp/utility/functional/plus

answered Jul 27 '17 at 23:07

Curious

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score -2 · Answer 2 · answered Jul 27 '17 at 23:15

-2

I've solved the issue either removing std namespace or changing the function name is all it takes!

answered Jul 27 '17 at 23:15

SS2

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c++ template ambiguous error

2 Answers2