Question

LINUX下多线程编译问题

#include<stdio.h>
#include<pthread.h>
#include<unistd.h>
#include<semaphore.h>
void *producter_f (void *arg); //生产者线程函数
void *consumer_f (void *arg); //消费者线程函数
sem_t sem;
int running=1;
int main(void)
{
pthread_t consumer_t;
pthread_t producter_t;
sem_init(&sem,0,10); //信号量初始化
pthread_create(&producter_t,NULL,(void*)producter_f,NULL);
pthread_create(&consumer_t,NULL,(void*)consumer_f,NULL);
sleep(1);
running=0;
pthread_join(consumer_t,NULL);
pthread_join(producter_t,NULL);
sem_destroy(&sem);
return 0;
}
void *producter_f (void *arg)
{
int semval=3;
while(running)
{
usleep(2);
sem_post(&sem);
sem_getvalue(&sem,&semval);
printf("生产，总数量:%d\n",semval);
}
}
void *consumer_f (void *arg)
{
int semval=0;
while(running)
{
usleep(3);
sem_wait(&sem);
sem_getvalue(&sem,&semval);
printf("消费，总数量:%d\n",semval);
}
}
编译过程中总是出现各种变量未定义的现象，求解这是为什么

Answer 1

你编译的时候有加多扮答线程连接选项吗？ 要加上 -lpthread 或者厅毁慧 -pthread (尽量选后者)
例如 gcc -pthread -o test main.cpp

另外你的线程创建的不对，函数指针不能强转类型（这里也不用转）余李
pthread_create(&producter_t,NULL,(void*)producter_f,NULL);
pthread_create(&consumer_t,NULL,(void*)consumer_f,NULL);

应该是
pthread_create(&producter_t,NULL,producter_f,NULL);
pthread_create(&consumer_t,NULL,consumer_f,NULL);