std::basic_filebuf::operator=(3)

NAME
std::basic_filebuf::operator= - std::basic_filebuf::operator=

Synopsis
   std::basic_filebuf& operator=( std::basic_filebuf&& rhs ); (1) (since C++11)
   std::basic_filebuf& operator=( const std::basic_filebuf& rhs ) = (2)
   delete;
   Assigns another basic_filebuf object.
   1) First calls close() to close the associated file, then moves the contents of rhs
   into *this: the put and get buffers, the associated file, the locale, the openmode,
   the is_open flag, and any other state. After the move, rhs is not associated with a
   file and rhs.is_open() == false.
   2) The copy assignment operator is deleted; basic_filebuf is not CopyAssignable.

Parameters
   rhs - another basic_filebuf that will be moved from

Return value
   *this

Example
// Run this code
 #include <cassert>
 #include <fstream>
 #include <iostream>
 #include <string>
 int main()
 {
     std::ofstream{"test.in"} << "test\n"; // writes via a temporary object
     std::ifstream fin("test.in"); // read-only stream
     std::ofstream fout("test.out"); // write-only stream
     std::string s;
     std::getline(fin, s);
     std::cout << "s = [" << s << "]\n"; // s contains "test"
     assert(fout.is_open());
     *fin.rdbuf() = std::move(*fout.rdbuf());
     assert(!fout.is_open());
     std::getline(fin, s);
     std::cout << "s = [" << s << "]\n"; // s is empty input
 }

Output:
 s = [test]
 s = []

See also
   constructor constructs a basic_filebuf object
                 (public member function)
   swap swaps two basic_filebuf objects
   (C++11) (public member function)