How do I parse arrays in C++ for duplicates

Please help me use C++ to parse an array and only display numbers that are unique. I have written a program which answers most of the question below.

Question: Use a one-demensional array to solve the following problem. Read in 20 numbers, each of which is between 10 and 100, inclusive. As each number is read, validate and store it in the array only if it isn't a duplicate of a number already read. After reading all the values, display only the unique values that the user entered. Provide for the "worst case" in which all 20 number are different. Use the smallest possible array to solve this problem.

What I've done: My program creates a 20 item array. Prompts user for data, validates it and displays it. I have tried several way to only display unique data, however I have not accomplished what the question asks.

Sample User Input:

11, 12, 12, 12, 13, 14, 15, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27

My Program Output:

{ 11, 12, 12, 12, 13, 14, 15, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 }

Correct Program Output:

{ 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 }

Any advice where to go with this. See below for code. Thank you for your help!

#include <iostream>  
#include <array> // needed for c++11 arrays
using namespace std;

int main()
{
    const int arraySize = 20; // limit array length to 20
    array  <int, arraySize userArray>  = {}; 

    //Populate array with user input and validate it to be between 10 and 100

    for (int i = 0; i < userArray.size(); i++)
    {
            cout << "Enter a number between 10 and 100" << endl;
            cin >> userArray[i]; // get user input assign it to proper array subscript

            while(userArray[i] > 100 || userArray[i] < 10)//validate user input to be between 10 and 100
            {
                    cout << "Number needs to be between 10 and 100. Enter a new number" << endl;
                    cin >> userArray[i]; //reassign the proper array subscript if needed
            }

    }

    cout << endl;

    //display the information to look like an array
    //result looks like [ v, w, x, y, z ]

    cout << "[ ";
    //display array values
    for (int i = 0; i < userArray.size() - 1; i++)
    {
            cout << userArray[i] << ", ";
    }
    //properly display last array item
    cout << userArray[(userArray.size() - 1)] << " ]" << endl;


    return 0; }