c threads

main.c

// gcc -g main.c -o a -lpthread

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

typedef pthread_mutex_t mutex_t;

typedef struct {
  int* ary;
  mutex_t* mtx;
} thread_fn_args;

void insert_to_ary(int* ary, int val, int offset, mutex_t* mtx) {
  pthread_mutex_lock(mtx);
  *(ary + offset) = val;
  pthread_mutex_unlock(mtx);
}

/* main() for a thread */
void* thread_fn(thread_fn_args* args) {
  int i = 0;
  int* ary = args->ary;
  mutex_t* mtx = args->mtx;
  while (i < 110) {
    insert_to_ary(ary, i * -1, i, mtx);
    ++i;
  }
}

int main(int argc, char* args[]) {
  pthread_t t_hnd;
  mutex_t mtx;
  int i = 110;
  int* ary = malloc(210 * sizeof(int));
  printf("ary address: %p\n", (void*) ary);

  thread_fn_args thread_args;
  thread_args.ary = ary;
  thread_args.mtx = &mtx;

  pthread_create(&t_hnd, NULL, thread_fn, &thread_args);
  pthread_mutex_init(&mtx, NULL);

  while (i < 210) {
    insert_to_ary(ary, i, i, &mtx);
    ++i;
  }

  printf("main waiting for thread to terminate\n");
  pthread_join(t_hnd, NULL);

  for (i = 0; i < 210; ++i) {
    printf("%d ", *(ary + i));
  }

  free(ary);
  ary = NULL;
  return 0;
}