sort and remove duplicates from int array in c

Question

I am learning C and came over the topic of sorting. I wrote a comp() function in and used qsort to sort an array of int. Now for the next task I need to remove the duplicates from the array.
Is it possible to sort and remove duplicates at the same time?

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>    
int indexes[10] = { 0, 98, 45, 65, 45, 98, 78, 56, 65, 45 };

int comp(const void * elem1, const void * elem2) {

    int f = *((int*) elem1);
    int s = *((int*) elem2);

    if (f > s) {    
        return 1;
    }    
    if (f < s) {    
        return -1;
    }    
    return 0;
}

void printIndexArray() {    
    int i = 0;    
    for (i = 0; i < 10; i++) {    
        printf("i is %d\n", indexes[i]);    
    }
}

int main() {    
    qsort(indexes, sizeof(indexes) / sizeof(int), sizeof(int), comp);    
    printIndexArray();    
    return 0;
}

Answer 1

Since your numbers are already sorted, removing dupes is easy. In C++, it's even built in as std::unique:

http://en.cppreference.com/w/cpp/algorithm/unique

Assuming you want to do it yourself, you can do it the same way unique does it:

int* unique (int* first, int* last)
{
  if (first==last) return last;

  int* result = first;
  while (++first != last)
  {
    if (!(*result == *first)) 
      *(++result)=*first;
  }
  return ++result;
}

Answer 2

Yes

This can be achieved by mergesort. If both left and right are the same just merge the one value