sample.c

linux下线程的典型例子

#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <math.h>
#include <pthread.h>
#include <semaphore.h>

void print_message_function1( void *ptr );
void print_message_function2( void *ptr );

static	sem_t	*g_sem1 , *g_sem2 ;

int main( int argc , char **argv )
{
     pthread_t thread1, thread2;
     char *message1 = "Thread 1";
     char *message2 = "Thread 2";
     int  iret1, iret2;

	g_sem1 = ( sem_t * ) malloc( sizeof ( sem_t ) ) ;
	if ( NULL != g_sem1 ) {
		sem_init( g_sem1 , 0 , 1 ) ;
	}
	g_sem2 = ( sem_t * ) malloc( sizeof( sem_t ) ) ;
	if ( NULL != g_sem2 ) {
		sem_init( g_sem2 , 0 , 1 ) ;
	}

    /* Create independant threads each of which will execute function */

     iret1 = pthread_create( &thread1, NULL, (void*)&print_message_function1, (void*) message1);
     iret2 = pthread_create( &thread2, NULL, (void*)&print_message_function2, (void*) message2);

     /* Wait till threads are complete before main continues. Unless we  */
     /* wait we run the risk of executing an exit which will terminate   */
     /* the process and all threads before the threads have completed.   */

     //pthread_join( thread1, NULL);
//     pthread_join( thread2, NULL); 

     printf("Thread 1 returns: %d\n",iret1);
     printf("Thread 2 returns: %d\n",iret2);

	sem_destroy( g_sem1 ) ;
	sem_destroy( g_sem2 ) ;

//	printf( "sin( 0.6 ) is %f\n" , sin( 0.6 ) ) ;

     exit(0);
}

void print_message_function1( void *ptr )
{
     char *message;

	for ( ; ; ) {
		sem_wait( g_sem1 ) ;
		message = (char *) ptr;
		printf("%s \n", message);
		sem_post( g_sem2 ) ;
	}
}

void print_message_function2( void *ptr )
{
     char *message;

	for ( ; ; ) {
		sem_wait( g_sem2 ) ;
		message = (char *) ptr;
		printf("%s \n", message);
		sem_post( g_sem1 ) ;
	}
}