如何将 int 打印到 std::wcerr？

Question

如果我的对象需要打印std::wstring 以及整数等，我该如何编写输出operator<<？

#include <iostream>

struct Foo {
  int i;
  std::wstring wstr;
};

std::ostream& operator<<(std::ostream& out, Foo const& foo) {
  out << foo.i << foo.wstr; // error                                                                                            
  return out;
}

int main() {
  Foo foo;
  std::wcerr << foo << std::endl;
}

换句话说：如果我传递了wcerr，我如何打印ints 和其他原始数据类型？我需要boost::lexical_cast<std::wstring> 或类似的吗？

Answer 1

#include <iostream>

struct Foo {
   int i;
   std::wstring wstr;
};

std::wostream& operator<<(std::wostream& out, Foo const& foo) {
   out << foo.i << foo.wstr;                                                                                             
   return out;
}

int main() {
   Foo foo;
   std::wcerr << foo << std::endl;
}