Problems implementing a quicksort

Question

Got it working, final code: Pushes back data and sorts both in synchronization

#include "std_lib_facilities.h"

struct Name_pairs
{
       vector<string>names;
       vector<double>ages;
       void quicksort(vector<string>& num, vector<double>& num2, int top, int bottom);
       int divide(vector<string>& array, vector<double>& array2, int top, int bottom);
       bool test();
       string read_names();
       double read_ages();
       void print();
};

string Name_pairs::read_names()
{
       string name;
     cout << "Enter name: ";
     cin >> name;
     names.push_back(name);
     return name;
}

double Name_pairs::read_ages()
{
     double age;
     cout << "Enter corresponding age: ";
     cin >> age;
     ages.push_back(age);
     cout << endl;
     return age;
}

int Name_pairs::divide(vector<string>& array, vector<double>& array2, int top, int bottom)
{
    string x = array[top];
    int i = top-1;
    int j = bottom+1;
    string temp;
    double temp2;
    do{
        do
        {
             j--;
             }while(x<array[j]);

        do
        {
             i++;
             }while(x>array[i]);

        if(i<j)
        {
               temp = array[i];
               temp2 = array2[i];
               array[i] = array[j];
               array2[i] = array2[j];
               array[j] = temp;
               array2[j] = temp2;
               }
               }while(i<j);
        return j;
}


void Name_pairs::quicksort(vector<string>& num, vector<double>& num2, int top, int bottom)
{
     int middle;
     if(top < bottom)
     {
            middle = divide(num, num2, top, bottom);
            quicksort(num, num2, top, middle);
            quicksort(num, num2, middle+1, bottom);
            }
     return;
}

void Name_pairs::print()
{
     for(int i = 0; i < (names.size()-1) && i < (ages.size()-1); ++i)
             cout << names[i] << " , " << ages[i] << endl;
}

int main(){
    Name_pairs np;
    cout << "Enter names and ages. Use 0 to cancel.\n";
    bool finished = false;
    while(!finished){
    finished = "0" == np.read_names();
    finished = 0 == np.read_ages();}
    np.quicksort(np.names, np.ages, 0, (np.names.size()-2));
    np.print();
    keep_window_open();}

Answer 1

The following lines in main() should be deleted:

np.vector<string>names; // error possibly here?    
np.vector<double>ages;

They already exist as part of instantiating Name_pairs.

Also, remove the parameter names from quicksort since it isn't really necessary and will make your code not function the way you think it should. The names you want to sort are members of Name_pairs. The ones you declared in main() are not the ones you read in with read_names().

EDIT: Actually, it might be easier for you if you declare a single vector with a struct that contains the age and name and sort that array. The entirety of your program implies that you want to sort the names and then print out each name with the associated age, but you only sort the name array.

EDIT2: And from the other answers, I think you need to learn more about how to declare member functions before you can fully solve this problem.

Answer 2

If you're trying to define additional vector variables within main, then the lines

np.vector<string>names; // error possibly here?
np.vector<double>ages;

Should be:

vector<string> names;
vector<double> ages;

You're redefining your struct members, or so it seems. But I don't see where you'd actually use those. Also, size() returns an unsigned variable of some sort, so you may need to cast it, or change the way you're comparing it to prevent compiler errors/warnings.

It's also worth noting, that if you want a couple more vectors declared within main() then it's good practice to name them something unique instead of having them share names with the struct members. Also, your main() doesn't have a return (needs to return int).

Answer 3

Get rid of the following lines in main() which are apparently causing your compiler to crash:

np.vector<string>names; // error possibly here?    
np.vector<double>ages;

Then, a couple of your function definitions need to have their signatures changed:

int divide(vector<string>& array, int top, int bottom)

and

void quicksort(vector<string>& num, int top, int bottom)

need to change to

int Name_pairs::divide(vector<string>& array, int top, int bottom)

void Name_pairs::quicksort(vector<string>& num, int top, int bottom)

so they are seen as part of the Name_pairs struct instead of free functions.