/* File:     omp_lin_search.c
 *
 * Purpose:  Illustrate that OpenMP won't parallelize a for loop with
 *           a return statement.
 *
 * Compile:  gcc -g -Wall -fopenmp -o omp_lin_search omp_lin_search.c
 * Run:      Won't compile
 */
#include <stdio.h>
#include <stdlib.h>
#include <omp.h>

#define MAX 100000 

int thread_count;

int Lin_search(int A[], int n, int key);

int main(int argc, char* argv[]) {
   int i, n, key;
   int* A;

   if (argc != 2) {
      fprintf(stderr, "usage: %s <number of threads>\n", argv[0]);
      exit(0);
   }
   thread_count = strtol(argv[1], NULL, 10);
   printf("How many elements?\n");
   scanf("%d", &n);
   A = malloc(n*sizeof(int));

   srandom(1);
   for (i = 0; i < n; i++)
      A[i] = random() % MAX;
   key = random() % MAX;

   i = Lin_search(A, n, key);
   if (i == -1)
      printf("%d is not in the list\n", key);
   else
      printf("%d is in position %d\n", key, i);

   return 0;
}  /* main */

int Lin_search(int A[], int n, int key) {
   int i;

   /* This is going to cause a compile-time error */
#  pragma omp parallel for num_threads(thread_count) \
      default(none) shared(A, n, key) private(i)
   for (i = 0; i < n; i++)
      if (key == A[i]) return i;
   return -1;
}  /* Lin_search */