Problem with unique_copy

[Nobody/Anonymous]

This program (for an exercise in Stroustup's The C++ Programming Language) compiles fine, but crashes when it gets to unique copy.

#include <iostream>
#include <stdlib.h>
#include <vector>
#include <string>
#include <algorithm>

using namespace std;

int main()
{
    vector<string> words;
    vector<string> uniquewords;
    string input;
   
    do
    {
      cin >> input;
      if (input != "quit")
      {
         words.push_back(input);
      }
      else
      {
          break;
      }
    }while(input != "quit");
   
    cout << endl << endl;
   
    unique_copy(words.begin(), words.end(), uniquewords.begin());
   
    for (int loop=0; loop<uniquewords.size(); loop++)
    {
        cout << uniquewords[loop] << endl;
    }
   
    cout << endl << endl;
    system("PAUSE");
    return 0;
}

[Nobody/Anonymous]

Your problem is with cin

Learn more about it.

BlakJak  :]

[Nobody/Anonymous]

Indeed?

As far as I can see cin is doing it's job.

words contains a valid vector of words.

[Nobody/Anonymous]

What is unique_copy doing???

BlakJak    :]

[Nobody/Anonymous]

What is it doing?

Crashing: Unhandled acception -  access violation

What is it supposed to do?

As far as I am aware it is supposed to copy elements from one container to another, ensuring that only one instance of any element occurs in the destination container.

[Nobody/Anonymous]

I've got it.

Should have been:

unique_copy(words.begin(), words.end(), back_inserter(uniquewords));

instead of:

unique_copy(words.begin(), words.end(), uniquewords.begin());

This version would only have worked if there had already been something in uniquewords to overwrite.