direct accessing array of vectors in a vector

Question

I have several vectors that are being saved in a vector. I have to do certain logic operations on them, if the operations are successfully done, i have to store that vector which is saved in arrayOfUsers. issue is I cannot access the specific vector stored inside the arrayOfusers

example: arrayOfUsers has 3 vectors stored inside it, afer it passes the logic operations i have to write the vector number 2 in a file. I cannot access directly the vector by index inside arrayOfUsers

  vector<string> usersA ("smith","peter");
  vector<string> usersB ("bill","jack");
  vector<string> usersC ("emma","ashley");


  vector<vector<string>> arrayOfUsers;

  arrayOfUsers.push_back(usersA);
  arrayOfUsers.push_back(usersB);
  arrayOfUsers.push_back(usersC);

I run for loop

for ( auto x=arrayOfUsers.begin(); x!=arrayOfUsers.end(); ++x)
   {

    for (auto  y=x->begin(); y!=x->end(); ++y) 

       {

              //logic operations
       }

           if(logicOperationPassed== true)
           {
                // i cannot access the vector here, which is being pointed by y
                //write to file the vector which passed its logic operation
                // i cannot access x which is pointed to the arrayOfUsers

                // ASSUMING that the operations have just passed on vector index 2, 
                 //I cannot access it here so to write it on a file, if i dont write
                 //it here, it will perform the operations on vector 3

           }
    }

Answer 1

Why do you think "y" is pointing at a vector? Looks like it should be pointing at a string.

x is one element from "arrayOfUsers", y is one element from one of those.

FWIW - you seem to be using some c++11 features (auto) while not going all the way. Why not something like:

string saved_user;
for (const vector<string>& users : arrayOfUsers) {
  for (const string& user : users) {
    ...
    ... Logic Operations and maybe saved_user = user ...
  }
  // If you need access to user outside of that loop, use saved_user to get to
  // it. If you need to modify it in place, make saved_user a string* and do 
  // saved_user = &user. You'll also need to drop the consts.
}

The naming will be clearer as to what you're dealing with at each level, and the types are trivial, so no major gains from auto.

Answer 2

#include <iostream>
#include <vector>
#include <string>

using namespace std;

int main()
{
    vector<string> usersA;
    vector<string> usersB;
    vector<string> usersC;

    usersA.push_back("Michael");
    usersA.push_back("Jackson");

    usersB.push_back("John");
    usersB.push_back("Lenon");

    usersC.push_back("Celine");
    usersC.push_back("Dion");

    vector <vector <string > > v;
    v.push_back(usersA);
    v.push_back(usersB);
    v.push_back(usersC);

    for (vector <vector <string > >::iterator it = v.begin(); it != v.end(); ++it) {
        vector<string> v = *it;
        for (vector<string>::iterator it2 = v.begin(); it2 != v.end(); ++it2) {
            cout << *it2 << " ";
        }
        cout << endl;
    }


}