#include <sstream>string str() const;void str(string &s)
The str( ) function is a member of stringstream, istringstream, and ostringstream.
The first form of str( ) returns a string object that contains the current contents of the string-based stream.
The second form frees the string currently contained in the string stream and substitutes the string referred to by s.
Related functions are get( ) and put( ).