std::ostreambuf_iterator::ostreambuf_iterator(3)

NAME
std::ostreambuf_iterator::ostreambuf_iterator - std::ostreambuf_iterator::ostreambuf_iterator

Synopsis
   ostreambuf_iterator( streambuf_type* buffer ) (until C++11)
   throw();
   ostreambuf_iterator( streambuf_type* buffer ) (since C++11)
   noexcept; (1)
   ostreambuf_iterator( ostream_type& stream ) (until C++11)
   throw(); (2)
   ostreambuf_iterator( ostream_type& stream ) (since C++11)
   noexcept;
   1) Constructs the iterator with the private streambuf_type* member set to buffer and
   the failed() flag set to false. The behavior is undefined if buffer is a null
   pointer.
   2) Same as ostreambuf_iterator(stream.rdbuf()).

Parameters
   stream - the output stream whose rdbuf() will be accessed by this iterator
   buffer - the output stream buffer to be accessed by this iterator

Example
// Run this code
 #include <fstream>
 #include <iostream>
 #include <iterator>
 int main()
 {
     const char* file = "test.txt";
     {
         std::basic_filebuf<char> f;
         f.open(file, std::ios::out);
         std::ostreambuf_iterator<char> out1(&f);
         *out1 = 'a'; // writes to file via iterator
     }
     // read back from the file
     char a;
     std::cout << ((std::ifstream{file} >> a), a) << std::endl;
     std::ostreambuf_iterator<wchar_t> out2{std::wcout};
     *out2 = L'b';
 }

Output:
 a
 b
   Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
     DR Applied to Behavior as published Correct behavior
   LWG 112 C++98 the requirement "the argument cannot applies to overload
                      be null" was applied to overload (2) (1) instead
   P2325R3 C++20 default constructor was provided as C++20 removed along with
                      iterators must be default_initializable the requirement