Sample of custom C++ stream processing with custom destination if necessary

custom_stream.cpp

#include<iostream>
#include<sstream>

class CustomBuf : public std::stringbuf
{
public:
    virtual int sync() {
        // do whatever you want with this->str() here
        std::cout << "Syncing stream: " << this->str() << std::endl;
    }
};

int main()
{
    CustomBuf cb;
    std::ostream stream(&cb);
    stream << "Hello custom stream processing with custom destination" << std::flush;
    return 0;
}