std::wostream_iterator
c++, iterator, wofstream
Solution
Because `std::ostream_iterator` is not `typedef` (and `std::wstring` is typedef on `std::basic_string` with `charT` = `wchar_t`).
template <class T, class charT = char, class traits = char_traits<charT> >
class ostream_iterator:
public iterator<output_iterator_tag, void, void, void, void>
Second copy operation
std::copy(myvec.begin(), myvec.end(), std::ostream_iterator<std::wstring>(f));
is incorrect, since
typedef basic_ostream<charT,traits> ostream_type;
so, in this case `ostream_type` is `basic_ostream<char, std::char_traits<char> >`
ostream_iterator(ostream_type& s);
Constructor can receive only this type, but we pass `basic_ofstream<wchar_t, std::char_traits<wchar_t> >`, it's incorrect.
Problem
Why there are no std::wostream_iterator in C++? Is there any good reason for this? ``` #include <fstream> #include <iterator> #include <string> #include <vector> int main() { std::vector<std::wstring> myvec = { L"first", L"second" }; std::wofstream f("New.txt"); // std::copy(myvec.begin(), myvec.end(), std::wostream_iterator<std::wstring>(f)); // Error // std::copy(myvec.begin(), myvec.end(), std::ostream_iterator<std::wstring>(f)); // Error std::copy(myvec.begin(), myvec.end(), std::ostream_iterator<std::wstring, wchar_t>(f)); // Ok std::copy(myvec.begin(), myvec.end(), std::ostream_iterator<std::wstring, wchar_t, std::char_traits<wchar_t>>(f)); // Ok } ```