seekp() on empty stringstream

[clros]

Hi!

Aren't possible to use seekp() method on an empty stringstream?

I would like make a string, moving freely inside it for store infos, not in order of insertion, using seekp() to determine where to write it...

[LB]

I'd suggest a std::map<unsigned long, std::string> for that. You can think of the key as the 'position', and iterating the map will go in order of least to greatest.

[Cubbi]

if it's empty, there is nowhere to move with seekp(). But you could make a fixed-size string stream:

#include <iostream>
#include <string>
#include <sstream>
int main()
{
    std::ostringstream os(std::string(10, '*'));
    os.seekp(3);
    os << 1;
    os.seekp(8);
    os << 2;
    std::cout << os.str() << '\n';
}

demo: http://ideone.com/yvLwv

Granted, it's not the intended use of a string stream, there may be better ways to achieve your goals.