// CS 450; Thread example 2: Pass argument to thread
// version 2014-01-25 3:43 PM
//
#include <pthread.h>
#include <stdio.h>

void *task(void *arg);  // prototype

int main(void) {
	pthread_t thd;		// thread
	int retcode;		// 0 if thread creation succeeded
	int thd_arg = 17;	// argument to pass to thread

	// Create thread and have it run task; pass pointer to
	// thread argument.
	//
	retcode = pthread_create(&thd, NULL, task, (void *) &thd_arg);
	printf("Thread creation returned code = %d\n", retcode);
	printf("Thread argument at %p\n", &thd_arg);

	// Wait for thread to finish
	//
	pthread_join(thd, NULL);
}

// Thread task takes pointer to an argument value.
//
void *task(void *arg) {
	int *my_arg_ptr = (int *) arg;
	int my_arg = *my_arg_ptr;
	printf("Thread called with argument %d at %p\n", my_arg, arg);
	return NULL;
}

/* Output:

Thread creation returned code = 0
Thread called with argument 17 at 0x7fff5c89dac8
Thread argument at 0x7fff5c89dac8

*/

// Note: Last two lines could be swapped