以分离状态创建线程

int makethread(void * (*fn)(void *),void * arg)
{
        int err;
        pthread_t tid;
        pthread_attr_t attr;

        err=pthread_attr_init(&attr);
        if(err!=0)
                return (err);
        err=pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED);
        if(err==0)
                err=pthread_create(&tid,&attr,fn,arg);
        pthread_attr_destroy(&attr);
        return err;
}