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std::basic_ios::rdbuf(3) C++ Standard Libary std::basic_ios::rdbuf(3)


std::basic_ios::rdbuf - std::basic_ios::rdbuf


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

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.


sb - stream buffer to associate to

Return value

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


May throw implementation-defined exceptions.


// 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

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

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


back to default buffer
local content: some message

See also

set_rdbuf replaces the rdbuf without clearing its error state
(protected member function)