/* helloThreads.c
 * This is a multi-threaded "hello world"
 * Each thread prints "hello". and they are not guaranteed to do so in the order they were created.
 *
 * gcc -o hello -lpthread helloThread.c
 *
 */
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>


#define NUM_THREADS	5

typedef struct {
	int id;
} threadInfo;

// the main function for a pthread must return a void * and have a single void* as its input
void *hello_thread(void *threadinfo) {
	threadInfo *ti = (threadInfo *) threadinfo;
	printf("Thread %d", ti->id );
	printf( " saying Hello!\n");
	pthread_exit(NULL);
}

int main () {
	int i;
	threadInfo ti[NUM_THREADS];
	pthread_t thread[NUM_THREADS];
	
	// Set up the parameters for each thread
	for (i = 0; i < NUM_THREADS; i++) 
		ti[i].id = i;
	
	// Get the threads going
	for (i = 0; i < NUM_THREADS; i++)  {
		pthread_create(&(thread[i]), NULL, hello_thread, &(ti[i]));
	}
	
	// Join up with them. This will wait until they are done.
	// If we don't have this hear, then the main program ends before
	// the threads complete their tasks
	for (i = 0; i < NUM_THREADS; i++) 
		pthread_join(thread[i], NULL);

    // If we sleep instead of joining, that gives some threads time to finish
    // their tasks
	//sleep(1);
	
	return 0;
}