CODEWITHSUNDEEP
c++templatesiterator
Dominik
Dominik

Reputation: 59

c++ no matching function for call to: passing iterators?

I've encountered a strange problem in my C++ Code. I've defined a TemplateClass called 

StateTemplate<T>

Furthermore I defined 

typedef StateTemplate<double> StateDouble.

Then I defined a friend function

template<class S>
friend S partialEntangledScalarProduct(
    const typename std::vector<StateTemplate<T> >::const_iterator s1,
    const typename std::vector<StateTemplate<T> >::const_iterator s2,
    const typename std::vector<StateTemplate<T> >::const_iterator sSub1,
    const typename std::vector<StateTemplate<T> >::const_iterator sSub2,
    vector<unsigned int> const &pos,
    vector<unsigned int> const &posNot);

If I now make

std::vector<StateDouble>::const_iterator s1;
std::vector<StateDouble>::const_iterator s2;
std::vector<StateDouble>::const_iterator sSub1;
std::vector<StateDouble>::const_iterator sSub2;

vector<unsigned int> vui;

Doub test=partialEntangledScalarProduct(s1,s2,sSub1,sSub2,vui,vui);

I get the following Error:

no matching function for call to 
    'partialEntangledScalarProduct(
         __gnu_cxx::__normal_iterator<
             const StateTemplate<double>*,
             std::vector<
                 StateTemplate<double>,
                 std::allocator<StateTemplate<double> > > >&,
         __gnu_cxx::__normal_iterator<
             const StateTemplate<double>*,
             std::vector<
                 StateTemplate<double>,
                 std::allocator<StateTemplate<double> > > >&,
         __gnu_cxx::__normal_iterator<
             const StateTemplate<double>*,
             std::vector<
                 StateTemplate<double>,
                 std::allocator<StateTemplate<double> > > >&,
         __gnu_cxx::__normal_iterator<
             const StateTemplate<double>*,
             std::vector<
                 StateTemplate<double>,
                 std::allocator<StateTemplate<double> > > >&,
         const std::vector<unsigned int, std::allocator<unsigned int> >&,
         std::vector<unsigned int, std::allocator<unsigned int> >&)'

I've tried for hours to find the problem, but it seems that I overlook something. Maybe someone could help me?

best regards Dominik

p.s.: if you need more information about my code, just let me know. At the moment I just wanted to give you the important parts.

Here is a small example with the same error. 

#include <iostream>
#include <vector>

template<class T>
class StateTemplate{
    template<class S>
    friend S testFunction(
        const typename std::vector<StateTemplate<S> >::const_iterator s1);
public:
StateTemplate();
};

template<class T>
StateTemplate<T>::StateTemplate(){}

template<class T>
T testFunction(
        const typename std::vector<StateTemplate<T> >::const_iterator s1)
{
    return T(1);
}

int main(){
    std::vector<double>::const_iterator s1;
    double s=testFunction<double>(s1);
    return 0;
}

Upvotes: 1

Views: 1826

Answers (2)

Andriy
Andriy

Reputation: 8604

If you presented the declaration of partialEntangledScalarProduct correctly, the template parameter S isn't used anywhere in the function parameter list. Therefore, the compiler would never deduce it and you have to provide it explicitly.

partialEntangledScalarProduct<SomeClass>(s1,s2,sSub1,sSub2,vui,vui);

SomeClass is just an example, the exact name is unclear unless you provide more details.

Upvotes: 2

moswald
moswald

Reputation: 11677

(I don't have g++ on this machine, so this is conjecture.)

I think the issue is that the compiler can't deduce S and you're getting an unhelpful error message. Change your usage to the following:

double test = partialEntangledScalarProduct<double>(s1,s2,sSub1,sSub2,vui,vui);

As a side note, make sure your examples compile for you before you post them. I'm assuming Doub was supposed to be double?

Upvotes: 1

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