reverse words in a sentence using istringstream and istream_iterator

Trying to solve the problem using C++ constructs. Reference to each word in the sentence is taken and reversed. But the changes are not seen in the original sentence.

class Solution {
public:
    string reverseWords(string s) {
        istringstream ss(s);
        for(auto w = istream_iterator<string>(ss); w != istream_iterator<string>(); w++)
        {
            /* changes of the below 2 lines are not reflected in the main sentence*/
            string &str = const_cast<string&>(*w);
            reverse(str.begin(),str.end());           
        }
        reverse(s.begin(),s.end());
    return s;
    }
};