pthread小程序--1

/* thread_example.c
*/
#include
#include
#include
#include

#define MAX 10

pthread_t thread[2];
pthread_mutex_t mut;
int num = 0;
int i = -1;

void *thread1()
{
    printf("thread1: l am thread 1\n");
    for(i = 0; i < MAX; i++)
    {
        printf("thread1:num = %d\n",num);
        pthread_mutex_lock(&mut);
        num++;
        pthread_mutex_unlock(&mut);
        sleep(2);
    }
    printf("thread1: master function waiting for me to done?\n");
    pthread_exit(NULL);
}
void *thread2()
{
    printf("thread2: l am thread2\n");
    for(i = 0; i < MAX; i++)
    {
        printf("thread2:num = %d\n",num);
        pthread_mutex_lock(&mut);
        num++;
        pthread_mutex_unlock(&mut);
        sleep(3);
    }
    printf("thread2: master function is waiting for me? \n");
    pthread_exit(NULL);
}

void thread_create(void)
{
    int temp = -1;
    memset(&thread, 0, sizeof(thread));
    if( 0 != (temp = pthread_create(&thread[0], NULL, thread1, NULL)) )
    {
        printf("create thread1 failed\n");
    }
    else
    {
        printf("create thread1 success\n");
    }

    if( 0 != (temp = pthread_create(&thread[1], NULL, thread2, NULL)) )
    {
        printf("create thread2 failed\n");
    }
    else
    {
        printf("create thread2 success\n");
    }
}

void thread_wait(void)
{
    if(0 != thread[0])
    {
        pthread_join(thread[0], NULL);
        printf("now thread1 is over\n");
    }
    if(0 != thread[1])
    {
        pthread_join(thread[1], NULL);
        printf("now thread2 is over\n");
    }
}

int main()
{
    pthread_mutex_init(&mut, NULL);
    printf("l am master function \n");
    thread_create();
    printf("l am master function,l am waiting for threads to over\n");
    thread_wait();
    return 0;
}

gcc -o thread_example -c thread_example.c -pthread
./thread_example 执行程序结果如下：
l am master function
create thread1 success
thread1: l am thread 1
create thread2 success
l am master function,l am waiting for threads to over
thread2: l am thread2
thread1:num = 0
thread2:num = 0
thread1:num = 2
thread2:num = 3
thread1:num = 4
thread2:num = 5
thread1:num = 6
thread1:num = 7
thread2:num = 8
thread1:num = 9
thread2:num = 10
thread1: master function waiting for me to done?
now thread1 is over
thread2: master function is waiting for me?
now thread2 is over

再次执行程序结果如下：
l am master function
create thread1 success
thread1: l am thread 1
create thread2 success
l am master function,l am waiting for threads to over
thread1:num = 0
thread2: l am thread2
thread2:num = 1
thread1:num = 2
thread2:num = 3
thread1:num = 4
thread2:num = 5
thread1:num = 6
thread1:num = 7
thread2:num = 8
thread1:num = 9
thread2:num = 10
thread1: master function waiting for me to done?
now thread1 is over
thread2: master function is waiting for me?
now thread2 is over
再次结果是不一样的：对于num的第一次的值，当thread1中num =0时，thread2中的num 就不应该再出现num = 0的可能了，但却出现了，反复执行程序，结果如上所示。
不知道这是为什么，请高手指点，谢谢。
线程相关的一些操作：
pthread_t-----> typedef unsigned long int pthread_t
pthread_create(pthread_t *thread, const pthread_attr_t *attr, void *(*start_routine)(void*), void *arg)

*thread：    指向线程start_rountine的ID

*attr：    线程start_rountine的属性值，

start_rountine：    待创建的新的线程

*arg：    传递给start_rountine的参数

线程的两种结束方式：一种是线程自己运行完了之后的结束，另外一种是采用pthread_exit结束

当线程还没有执行完的时候，有时候需要等待线程的结束，采用pthread_join()来等待线程的结束
int (pthread_t thread, void **retval);
pthread_t thread：指向线程的ID号
void **retval：用来保存线程执行后返回的值
当pthread_join()成功时返回0，否则，返回错误代码
把程序修改一下，也就是让线程结束pthread_exit(“XXXXXXX”)传递一些东西出去，如：
/* thread_example.c
*/
#include
#include
#include
#include

#define MAX 10

pthread_t thread[2];
pthread_mutex_t mut;
int num = 0;
int i = -1;

void *thread1()
{
    printf("thread1: l am thread 1\n");
    for(i = 0; i < MAX; i++)
    {
        printf("thread1:num = %d\n",num);
        pthread_mutex_lock(&mut);
        num++;
        pthread_mutex_unlock(&mut);
        sleep(2);
    }
    printf("thread1: master function waiting for me to done?\n");
    pthread_exit("------------------thread1\n");
}
void *thread2()
{
    printf("thread2: l am thread2\n");
    for(i = 0; i < MAX; i++)
    {
        printf("thread2:num = %d\n",num);
        pthread_mutex_lock(&mut);
        num++;
        pthread_mutex_unlock(&mut);
        sleep(3);
    }
    printf("thread2: master function is waiting for me? \n");
    pthread_exit("this is thread2----------->\n");
}

void thread_create(void)
{
    int temp = -1;
    memset(&thread, 0, sizeof(thread));
    if( 0 != (temp = pthread_create(&thread[0], NULL, thread1, NULL)) )
    {
        printf("create thread1 failed\n");
    }
    else
    {
        printf("create thread1 success\n");
    }

    if( 0 != (temp = pthread_create(&thread[1], NULL, thread2, NULL)) )
    {
        printf("create thread2 failed\n");
    }
    else
    {
        printf("create thread2 success\n");
    }
}

void *join1 = NULL;
void *join2 = NULL;
void thread_wait(void)
{
    if(0 != thread[0])
    {
        pthread_join(thread[0], &join1);
        printf("thread1 return value is:%s\n",join1);
        printf("now thread1 is over\n");
    }
    if(0 != thread[1])
    {
        pthread_join(thread[1], &join2);
        printf("thread2 return value is:%s\n",join2);
        printf("now thread2 is over\n");
    }
}

int main()
{
    pthread_mutex_init(&mut, NULL);
    printf("l am master function \n");
    thread_create();
    printf("l am master function,l am waiting for threads to over\n");
    thread_wait();
    return 0;
}

这个时候返回值就有结果了，运行一下可以看到返回值的结果。