Question

Need help studying for c++ class. We just learned about STL. And learns about iterators, vectors, templates and doubly link list and maps.

One of the challenge question is asking:

If we were given a map or a multimap, we would have to output the keys in reverse order and keep the values the same (meaning don’t reverse or change the order) using only 1 loop.

Can someone show me an example.

Answer 1

Source code:-
---------------------------
#include <iostream>
#include <map>
#include <iterator>
using namespace std;
int main()
{
    map<string,string>obj;
    obj["101"]="venkanna";
    obj["102"]="koothada";
    obj["103"]="prudhvi";
    obj["104"]="Madhu";
    obj["105"]="Narayana";
    cout<<"\nthe Key values in hashmap values are"<<endl;
    cout<<"\n-------------------------------------"<<endl;
    map<string, string> :: iterator itr;
    for(itr =obj.begin();itr!=obj.end();++itr)
    {
        cout<<itr->first<<"->\t"<<itr->second<<endl;
    }
    cout<<"\nthe reverse order of Key values in hashmap values are"<<endl;
    cout<<"\n-------------------------------------"<<endl;
    map<string, string> :: reverse_iterator itr2;
    for(itr2 =obj.rbegin();itr2!=obj.rend();++itr2)
    {
        cout<<itr2->first<<"->\t"<<itr2->second<<endl;
    }
    return 0;
}
sample output:-
-------------------------

the Key values in hashmap values are 101- enkanna 102-koothada 103 prudhui 104→ Madhu 105-Narayana the reverse order of Key values in hashmap values are 105-Narayana 104- Madhu 103- prudhui 102koothada 101-venkanna Process exited after 0.0758 seconds with return value0 Press any key to continue . - .