c++ - ostringstream breaks cout? -

i want output content of ostringstream other stream (for example std::cout). know can use std::ostringstream::str() assume has overhead on copying stream contents string , further other stream. found use std::ostringstream::rdbuf() (comment suggesting has 25 votes). breaks std::cout shown in output of test program below. doing wrong?

#include <iostream> #include <sstream>  int main(int argc, char const *argv[]) {     std::ostringstream ss;     ss << "some data" << std::endl;     std::cerr << std::cout << std::endl;     std::cout << "start" << std::endl;     std::cout << ss.str();     std::cout << ss.rdbuf();     std::cout << "end" << std::endl;     std::cerr << std::cout  << std::endl;     return 0; } 

results in:

0x6013b8 start data 0 

your problem rdbuf() buffer ostringstream is, might expect name, write only (the ostringstream returns string through str() method). can't read data out of through buffer pointer.

change ostringstream stringstream , should work fine.