To be tested...

streams.cpp

#include <iostream>
#include <string>
#include <sstream>

int main(int argc, char ** argv)
{
    std::string content;
    std::stringstream buffer;

    if (argc > 1)
    {
        //buffer.reserve(100000000);
        content.reserve(100000000);
        buffer.str(content);
        buffer.seekg(0);
        std::cout << "reserve memory" << std::endl;
    }

    std::cout << "size: " << buffer.str().size() << std::endl;

    for(int i=1; i<=1000000; ++i)
    {
        buffer << "blabla" << i;
        buffer << "zoozoo" << i + 2;
    }
    
    std::cout << "size: " << buffer.str().size() << std::endl;
}