// main.cpp
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#include <iostream>
#include <utility>
#include <algorithm>
#include <iterator>
#include <map>
template<typename t1, typename t2>
std::ostream& operator<<(std::ostream& os, const std::pair<t1, t2>& pair)
{
return os << "< " << pair.first << " , " << pair.second << " >";
}
int main()
{
std::map<int, int> map = { { 1, 2 }, { 2, 3 } };
std::cout << *map.begin() << std::endl;//This works
std::copy(
map.begin(),
map.end(),
std::ostream_iterator<std::pair<int,int> >(std::cout, " ")
); //this doesn't work
}
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no match for ‘operator<<’ …