The operator << must be defined in the boost namespace. See the error message of VC:see reference to function template instantiation 'std::basic_ostream<_Elem,_Traits> &boost::operator <<<char,std::char_traits<char>,std::vector<_Ty>,int,std::string,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_,boost::detail::variant::void_>(std::basic_ostream<_Elem,_Traits> &,const boost::variant<T0_,T1,T2> &)' being compiled VC looks for boost::operator<< function and not ::operator<< function. But this should be documented in OutputStreamable. This would compile: #include<iostream> #include<vector> #include<string> #include<boost/variant.hpp> namespace boost { template <typename T> std::ostream& operator<<(std::ostream& os, const std::vector<T>& v) { for(typename std::vector<T>::size_type i = 0; i < v.size(); ++i) os << v[i] << std::endl; return os; } } struct TpTemplateVariant { typedef boost::variant<std::vector<unsigned long>,int, std::string> BoostVariant; }; typedef TpTemplateVariant::BoostVariant Tpvariant; int main () { Tpvariant p(5); std::cout << p; return 0; } Good Luck, Ovanes Markarian On Mon, June 26, 2006 12:45, CLAIRE, Narinder, Group Risk Mgmt wrote:
I apologise for emailing you directly .. but i canno access the mailing list from work.. However in response to your response.
The following doesn't compile either .. I get the error
error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'const T0' (or there is no acceptable conversion)
On VC8
#include<iostream> #include<vector> #include<string>
#include<boost/variant.hpp>
std::basic_ostream<char> &operator<<(std::basic_ostream<char> &theostream,const std::vector<unsigned long> &theVector) { for(unsigned long i(0);i<theVector.size();i++) theostream << theVector[i] << "\n" ; return theostream; }
struct TpTemplateVariant { typedef boost::variant< std::vector<unsigned long>,
int,
std::string
BoostVariant; };
typedef TpTemplateVariant::BoostVariant Tpvariant;
int main () {
Tpvariant p(5); std::cout << p;
return 0;
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