似乎无法打印出我的字符串

Question

So this is a fragment of my code:

    void reverse(string query, string reverseQuery) {
        unsigned int i;

        for(i=0; i<query.length(); i++) {
            reverseQuery[i] = query[query.length()-1-i];
        }
        cout << reverseQuery << endl;
        return;
    }

The headers for iostream, string and using namespace std were also included in the code. The problem I am facing is that when I try to output the string reverseQuery nothing comes out. Anyone knows why? Thanks!

Answer 1

Your fragment should look like:

std::string reverse(const string& query) {
    std::string reverseQuery(query.length(),0); // <<<<< Ensure that the size is the same
    for(unsigned i=0; i<query.length(); i++) {
        reverseQuery[i] = query[query.length()-1-i];
    }
    // cout << reverseQuery << endl;
    return reverseQuery;
}

---

The way shorter and idiomatic code to achieve that with a standard c++ string is

std::string reverseQuery(query);
std::reverse(std::begin(reverseQuery),std::end(reverseQuery));