pthread - pthread_create(), pthread_join()

A simple program with threads. It also demostrates how the parameters are passed to the thread functions.

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

#define MAX_1    5
#define MAX_2   10  

/* ref: http://en.wikipedia.org/wiki/POSIX_Threads */

static void wait(void)
{
 time_t start_time = time(NULL);

 while (time(NULL) == start_time)
 {
     /* do nothing except chew CPU slices for up to one second */
 }
}

static void *thread_func1(void *vptr_args)
{
 int i;

 for (i = 1; i <= MAX_2; i++) {
      printf("[#1] (%2d/%2d) - %s\n", i, MAX_2, (char *)vptr_args);
      wait();
 }
 printf("[#1] --- End of #1 ---\n");

 return NULL;
}

static void *thread_func2(void *vptr_args)
{
 int i;

 for (i = 1; i <= MAX_2; i++) {
      printf("[#2] (%2d/%2d) - t_count = %d\n", i, MAX_2, (*(int *)vptr_args)++);
      wait();
 }
 printf("[#2] --- End of #2 ---\n");

 return NULL;
}

int main(void)
{
 int i;
 pthread_t thread_1, thread_2;
 char *t_param = "Hello Thread !";
 int   t_count = 1;

 pthread_create(&thread_1, NULL, thread_func1, (void *) t_param );
 pthread_create(&thread_2, NULL, thread_func2, (void *) &t_count);

 for (i = 1; i <= MAX_1; i++) {
     printf("[#0] (%2d/%2d) - t_count = %d \n", i, MAX_1, t_count);
     wait();
 }
 printf("[#0] --- End of #0 ---\n");

//    pthread_join(thread_1, NULL);
//    pthread_join(thread_2, NULL);

 printf("[  ] ------ End ------\n");

 return EXIT_SUCCESS;
}

Compile the source code with -lpthread. $ gcc pthread.c -o pthread -lpthread $ ./pthread

[#1] ( 1/10) - Hello Thread !
[#2] ( 1/10) - t_count = 1
[#0] ( 1/ 5) - t_count = 2
[#0] ( 2/ 5) - t_count = 2
[#1] ( 2/10) - Hello Thread !
[#2] ( 2/10) - t_count = 2
[#2] ( 3/10) - t_count = 3
[#1] ( 3/10) - Hello Thread !
[#0] ( 3/ 5) - t_count = 4
[#1] ( 4/10) - Hello Thread !
[#2] ( 4/10) - t_count = 4
[#0] ( 4/ 5) - t_count = 5
[#1] ( 5/10) - Hello Thread !
[#2] ( 5/10) - t_count = 5
[#0] ( 5/ 5) - t_count = 6
[#2] ( 6/10) - t_count = 6
[#0] --- End of #0 ---
[  ] ------ End ------

Oh ! Both threads are not completed when main program terminates. Uncomment both pthread_join() to wait threads terminate,

    pthread_join(thread_1, NULL);
    pthread_join(thread_2, NULL);

$ gcc pthread.c -o pthread_join -lpthread $ ./pthread_join

[#1] ( 1/10) - Hello Thread !
[#2] ( 1/10) - t_count = 1
[#0] ( 1/ 5) - t_count = 2
[#0] ( 2/ 5) - t_count = 2
[#1] ( 2/10) - Hello Thread !
[#2] ( 2/10) - t_count = 2
[#1] ( 3/10) - Hello Thread !
[#2] ( 3/10) - t_count = 3
[#0] ( 3/ 5) - t_count = 4
[#1] ( 4/10) - Hello Thread !
[#0] ( 4/ 5) - t_count = 4
[#2] ( 4/10) - t_count = 4
[#1] ( 5/10) - Hello Thread !
[#0] ( 5/ 5) - t_count = 5
[#2] ( 5/10) - t_count = 5
[#0] --- End of #0 ---
[#1] ( 6/10) - Hello Thread !
[#2] ( 6/10) - t_count = 6
[#2] ( 7/10) - t_count = 7
[#1] ( 7/10) - Hello Thread !
[#2] ( 8/10) - t_count = 8
[#1] ( 8/10) - Hello Thread !
[#1] ( 9/10) - Hello Thread !
[#2] ( 9/10) - t_count = 9
[#1] (10/10) - Hello Thread !
[#2] (10/10) - t_count = 10
[#1] --- End of #1 ---
[#2] --- End of #2 ---
[  ] ------ End ------

Main thread will wait another two threads by thread_join(). .