cool@archpony ~/D/e/p/c/goodcpp [1]> bat main.cpp
───────┬──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
       │ File: main.cpp
───────┼──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
   1   │ #include <iostream>
   2   │ #include <fstream>
   3   │ #include <string>
   4   │ 
   5   │ int main()
   6   │ {
   7   │     std::ostream placeToOutput = std::cout;
   8   │     std::string filename;
   9   │     std::cout << "Enter filename:" << std::endl;
  10   │     std::cin >> filename;
  11   │     if (false == filename.empty())
  12   │     {
  13   │         placeToOutput = std::ifstream(filename);
  14   │     }
  15   │     return 0;
  16   │ }
───────┴──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
cool@archpony ~/D/e/p/c/goodcpp> g++ main.cpp -o main
main.cpp: In function ‘int main()’:
main.cpp:7:39: error: use of deleted function ‘std::basic_ostream<_CharT, _Traits>::basic_ostream(const std::basic_ostream<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits<char>]’
    7 |     std::ostream placeToOutput = std::cout;
      |                                       ^~~~
In file included from /usr/include/c++/10.1.0/iostream:39,
                 from main.cpp:1:
/usr/include/c++/10.1.0/ostream:397:7: note: declared here
  397 |       basic_ostream(const basic_ostream&) = delete;
      |       ^~~~~~~~~~~~~
main.cpp:13:47: error: no match for ‘operator=’ (operand types are ‘std::ostream’ {aka ‘std::basic_ostream<char>’} and ‘std::ifstream’ {aka ‘std::basic_ifstream<char>’})
   13 |         placeToOutput = std::ifstream(filename);
      |                                               ^
In file included from /usr/include/c++/10.1.0/iostream:39,
                 from main.cpp:1:
/usr/include/c++/10.1.0/ostream:408:7: note: candidate: ‘std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator=(std::basic_ostream<_CharT, _Traits>&&) [with _CharT = char; _Traits = std::char_traits<char>]’
  408 |       operator=(basic_ostream&& __rhs)
      |       ^~~~~~~~
/usr/include/c++/10.1.0/ostream:408:33: note:   no known conversion for argument 1 from ‘std::ifstream’ {aka ‘std::basic_ifstream<char>’} to ‘std::basic_ostream<char>&&’
  408 |       operator=(basic_ostream&& __rhs)
      |                 ~~~~~~~~~~~~~~~~^~~~~