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

typedef struct {
  int * elements;
  int size;
} List;

void print_array( int *, int );
List find_all_inds( int *, int, int );

int main() {

  int * result;
  int numbers[] = { 1, 3, 5, 7, 9 };
  int values[] =  { 1, 3, 1, 1, 3, 5, 1, 3, 7, 9 };
  List list;

  print_array( numbers, 5 );

  list = find_all_inds( values, 10, 1 );
  printf( "size:  %d\n", list.size );
  printf( "\n" );

  free( list.elements );

  list = find_all_inds( values, 10, 3 );
  printf( "size:  %d\n", list.size );
  printf( "\n" );

}

List find_all_inds( int * list, int N, int value ) {

  int i, size;
  int * elements;
  List inds;

  for ( i = 0, size = 0; i < N; i++ ) {
    if ( *( list + i ) == value ) {
      // printf( "%d", i );
      size++;
    }
  }

  elements = malloc( size * sizeof( int ) );
  inds.elements = elements;
  inds.size = size;

  for ( i = 0; i < N; i++ ) {
    if ( *( list + i ) == value ) {
      *elements = i;
      elements++;
    }
  }

  return inds;
}

void print_array( int * i_ptr, int N ) {
  int i = 0;

  printf( "\n" );
  for ( i = 0; i < N; i++ ) {
    printf( "#%d:  %d\n", i, *( i_ptr + i ) );
  }

  printf( "\n" );
  for ( i = 0; i < N; i++, i_ptr++ ) {
    printf( "#%d:  %d\n", i, *i_ptr );
  }

  printf( "#%d:  %d\n", i, *i_ptr );
  printf( "\n" );
}