error when passing iterator to template function

Daniel Llorens del Río daniel.llorensdelrio@epfl.ch
Thu Apr 20 11:49:00 GMT 2006


On 19 Apr, 2006, at 20:56, Daniel Pape wrote:

> I'm simply trying to pass an iterator to a template function. Here is
> a simplified example that still has the error I'm seeing. I get
> (approximately) the same error with g++ 3.2.3, 3.3.6 and 3.4.5
>
> ---------------
> #include <vector>
>
> template <class T>
> void one(typename std::vector<T>::iterator it)
> {
>    (*it)++;
> }
>
> int main(int ac, char **av)
> {
>    std::vector<int> v(10);
>    one(v.begin());
>    return 0;
> }
> ---------------
>
>> g++ test.cpp
> test.cpp: In function `int main(int, char**)':
> test.cpp:12: error: no matching function for call to
> `one(__gnu_cxx::__normal_iterator<int*, std::vector<int,
> std::allocator<int> > >)'

Hi,

your problem is that iterator is in a 'non-deducible context'. Look  
for 'deducing template arguments' in the Stroustrup. If you cannot  
use the obvious alternative

template <class I>
void one(I it)
{
	(*it)++;
}

try looking into enable_if (this is in boost) and is_same (this is in  
std::tr1) for a more or less direct way to do what you want.






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