Working with stringstreams?

[zeromeus]

Hey all,

I'm not exactly sure how to work with sringstreams. I thought it'd work just like an IO stream, but I'm encountering this weird problem. Say I read in lines from a txt file and load it on to the stringstream, shouldn't I then be able to extract from the stringstream onto some other variable?

Say the file "data.txt" looks like this:

1
500
500
2
0.5
0.5

And the program looks like this:

int a;
std::string line;
std::stringstream ss (std::stringstream::in | std::stringstream::out);
std::ifstream file ("data.txt");
if (file.is_open())
{		
     std::getline (file,line);
     ss << line;
     std::cout << line <<"\n";
     ss >> a;
     std::cout << a << "\n";
}

When the contents of 'line' are printed, it accurately shows 1. But then when I supposedly extract it from the stringstream onto the int 'a' and print out 'a', I get the largest possible negative number for an int. I tried looking at the reference for stringstream, but I can't figure out what I'm doing wrong (it's probably something really stupid).

Thanks so much in advance!

[moorecm]

I'm not sure why that isn't working but I have always used ss.str(line); instead of stream insertion.

[zeromeus]

That still doesn't seem to work. The problem seems to be that whenever I try to extract from the stringstream onto a variable, it just doesn't go through if the variable had some value before. Like if a = 2, then when I use ss >> a, a will remain 2 no matter what value was in the string stream.

[zeromeus]

Sorry for double posting, but it seems that it actually has to do with extracting twice from the string stream.

I can extract once, but then every subsequent extraction just gives me gibberish. Why?

[LB]

Because you only get the first line with getline... You could just extract directly from the file, you know, it works the same way.

[zeromeus]

Wow, I'm an idiot. Yep, that's much cleaner and it actually works. Thanks!