How can I copy value from ostringstream to string?

Question

I tried :

ostringstream oss;
read a string from file and put to oss;
string str;
str << oss.str();// error here "error: no match for ‘operator>>’ in 'oss >> str' "

If I use str = oss.str(); Instead of printing the value of the string, it prints out "....0xbfad75c40xbfad75c40xbf...." likes memory address.
Can anybody tell me why? Thank you.

Answer 1

string str = oss.str(); // this should do the trick

Answer 2

If you're trying to copy the whole file to a stringstream, then this:

oss << ifs;

is wrong. All that does is prints the address of ifs. What you want to do is this:

oss << ifs.rdbuf();

And then of course, to copy that to a string, like the others are saying:

str = oss.str();

If you just want to get a single line, then skip the stringstream, and just use getline:

std::getline(ifs,str);