std::basic_ios<CharT,Traits>::rdbuf (3) - Linux Manuals

std::basic_ios<CharT,Traits>::rdbuf: std::basic_ios<CharT,Traits>::rdbuf

NAME

std::basic_ios<CharT,Traits>::rdbuf - std::basic_ios<CharT,Traits>::rdbuf

Synopsis

std::basic_streambuf<CharT, Traits>* rdbuf() const; (1)
std::basic_streambuf<CharT, Traits>* rdbuf( std::basic_streambuf<CharT, Traits>* sb ); (2)

Manages the associated stream buffer.
1) Returns the associated stream buffer. If there is no associated stream buffer, returns a null pointer.
2) Sets the associated stream buffer to sb. The error state is cleared by calling clear(). Returns the associated stream buffer before the operation. If there is no associated stream buffer, returns a null pointer.

Parameters

sb - stream buffer to associate to

Return value

The associated stream buffer, or a null pointer if there was no associated stream buffer.

Exceptions

(none)

Example

// Run this code

  #include <iostream>
  #include <sstream>

  int main()
  {
      std::ostringstream local;
      auto cout_buff = std::cout.rdbuf(); // save pointer to std::cout buffer

      std::cout.rdbuf(local.rdbuf()); // substitute internal std::cout buffer with
          // buffer of 'local' object

      // now std::cout work with 'local' buffer
      // you don't see this message
      std::cout << "some message";

      // go back to old buffer
      std::cout.rdbuf(cout_buff);

      // you will see this message
      std::cout << "back to default buffer\n";

      // print 'local' content
      std::cout << "local content: " << local.str() << "\n";
  }

Output:

  back to default buffer
  local content: some message