# Remove duplicates from a sorted array using STL in C++

• Difficulty Level : Basic
• Last Updated : 30 May, 2019

Given a sorted array, the task is to remove the duplicate elements from the array using STL in C++

Examples:

```Input: arr[] = {2, 2, 2, 2, 2}
Output: arr[] = {2}

Input: arr[] = {1, 2, 2, 3, 4, 4, 4, 5, 5}
Output: arr[] = {1, 2, 3, 4, 5}
```

Approach:
The duplicates of the array can be removed using the unique() function provided in STL.

Below is the implementation of the above approach.

 `#include ``using` `namespace` `std;`` ` `// Function to remove duplicate elements``void` `removeDuplicates(``int` `arr[], ``int` `n)``{`` ` `    ``// Initialise a vector``    ``// to store the array values``    ``// and an iterator``    ``// to traverse this vector``    ``vector<``int``> v(arr, arr + n);``    ``vector<``int``>::iterator it;`` ` `    ``// using unique() method to remove duplicates``    ``it = unique(v.begin(), v.end());`` ` `    ``// resize the new vector``    ``v.resize(distance(v.begin(), it));`` ` `    ``// Print the array with duplicates removed``    ``cout << ``"\nAfter removing duplicates:\n"``;``    ``for` `(it = v.begin(); it != v.end(); ++it)``        ``cout << *it << ``", "``;``    ``cout << ``'\n'``;``}`` ` `// Driver code``int` `main()``{``    ``int` `arr[] = { 1, 2, 2, 3, 4, 4, 4, 5, 5 };`` ` `    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]);`` ` `    ``// Print array``    ``cout << ``"\nBefore removing duplicates:\n"``;``    ``for` `(``int` `i = 0; i < n; i++)``        ``cout << arr[i] << ``" "``;`` ` `    ``// call removeDuplicates()``    ``removeDuplicates(arr, n);`` ` `    ``return` `0;``}`
Output:
```Before removing duplicates:
1 2 2 3 4 4 4 5 5
After removing duplicates:
1, 2, 3, 4, 5,
```

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