problems of template

[stereoMatching]

compiler : visual c++ 2010
os : windows 7 64bits

learning template and encounter some problem

template<typename T>
void easyCopyImpl(T const &A, typename boost::enable_if_c< boost::is_array<T>::value>::type *temp = 0)
{
	std::cout<<"this is array"<<std::endl;
	std::cout<<typeid(T).name()<<std::endl;
	std::copy(A, A + sizeof_array(A), typename std::ostream_iterator<T>(std::cout, "") );
}

template<typename T>
void easyCopyImpl(T const &A, typename boost::enable_if_c< boost::is_class<T>::value>::type *temp = 0)
{
	std::cout<<"this is class"<<std::endl;
	//std::copy(A.begin(), A.end(), std::ostream_iterator<T>(std::cout, "") );
}

template<typename T>
void easyCopy(T const &A)
{
	easyCopyImpl(A);
}

int main()
{
  int A[] = {1, 2, 3, 4};
  easyCopy(A);
}

It would pop out a lot of error messages
What is the problem and how could I solve it?Thanks

[sbonnalc]

Hello,
My guess is that the two easyCopyImpl templated methods have the same method signature (same name + same arguments type).
Try having a different method name and it should work.

[moorecm]

I'm not sure how enable_if_c works but I suspect it does name a different type for each of the functions. I would like to see the error message.

[JMJAtlanta]

To the best of my ability (which I admit is limited) I have taken your code and tried to make it compile on my system. Here is the code that includes the header files...

#include <boost/utility/enable_if.hpp>
#include <boost/type_traits/is_array.hpp>
#include <boost/type_traits/is_class.hpp>
#include <iostream>
#include <iterator>

template<typename T>
void easyCopyImpl(T const &A, typename boost::enable_if_c< boost::is_array<T>::value>::type *temp = 0)
{
	std::cout<<"this is array"<<std::endl;
	std::cout<<typeid(T).name()<<std::endl;
	std::copy(A, A + sizeof_array(A), typename std::ostream_iterator<T>(std::cout, "") );
}

template<typename T>
void easyCopyImpl(T const &A, typename boost::enable_if_c< boost::is_class<T>::value>::type *temp = 0)
{
	std::cout<<"this is class"<<std::endl;
	//std::copy(A.begin(), A.end(), std::ostream_iterator<T>(std::cout, "") );
}

template<typename T>
void easyCopy(T const &A)
{
	easyCopyImpl(A);
}

int main()
{
  int A[] = {1, 2, 3, 4};
  easyCopy(A);
}

The error I get is about sizeof_array not being found. Is that the error you're getting?

Just for grins, I replaced it with sizeof(), but get a problem about binary '=': no operator found which takes a right-hand operand of type 'const int', which is caused by line 12. If I comment out line 12, it compiles (but of course doesn't do much).

Please let us know what errors you are receiving, and we'll go from there.

[stereoMatching]

The error I get is about sizeof_array not being found. Is that the error you're getting?

no, that is not the problem
I am sorry I forgot to release the codes of sizeof_array

template<typename T, size_t size>
inline size_t const sizeof_array(T const (&)[size]){return size;}

the problem is because the compiler would deduce the type T as "int [4]" rather than "int"
so I simply have to remove "[4]"

template<typename T>
typename boost::enable_if< boost::is_array<T> >::type copy_out_impl(T const &A)
{
	std::cout<<"this is array : ";
	typename typedef boost::remove_extent<T>::type ValueType;	
	std::copy(A, A + sizeof_array(A), std::ostream_iterator<ValueType>(std::cout, "") );
	std::cout<<std::endl;
}

template<typename T>
typename boost::enable_if< boost::is_class<T> >::type copy_out_impl(T const &A)
{
	std::cout<<"this is class : ";
	typedef typename T::value_type ValueType;
	std::copy(A.begin(), A.end(), std::ostream_iterator<ValueType>(std::cout, "") );
	std::cout<<std::endl;
}

template<typename T>
void copy_out(T const &A)
{
	copy_out_impl(A);
}

Thanks for your help