Click here to download pos.c.

#include <stdio.h>
#include <stdlib.h>

int* positive(int* psizeptr, int* array, int size);

int main() {
  // read size n
  int n;
  do {
    printf("Enter size: ");
    fflush(stdout);
  } while(scanf(" %i", &n) != 1 || n <= 0);

  // allocate array and read in contents
  int* data = calloc(n, sizeof(int));
  printf("Enter %i integers, space separated.\n", n);
  for (int i=0; i<n; ++i) {
    scanf(" %i", &data[i]);
  }

  // CALL YOUR FUNCTION(S) HERE
  int psize;
  int* pos = positive(&psize, data, n);
  // AND PRINT OUT THE RESULTS
  for (int i = 0; i < psize; ++i) {
    printf("%i", pos[i]);
    if (i < psize-1) printf(", ");
  }
  printf("\n");

  // clean-up time
  free(data);
  free(pos);
  return 0;
}

int* positive(int* psizeptr, int* array, int size) {
  *psizeptr = 0;

  // first count the number of positive values
  for (int i=0; i < size; ++i) {
    if (array[i] > 0) {
      ++(*psizeptr);
    }
  }

  // allocate the new array
  int* result = calloc(*psizeptr, sizeof(int));
  int j = 0;

  // copy positive nums to the new array
  for (int i=0; i < size; ++i) {
    if (array[i] > 0) {
      result[j] = array[i];
      ++j;
    }
  }

  return result;
}