c编程中main函数中使用了库文件中定义的函数，编译时却提示该函数未定义，这是啥问题，坐等高手解答

Posted 2023-03-12

c源码如下
#include<pthread.h>
#include<stdio.h>
#include<stdlib.h>
#define REPEAT_NUM 5
#define DELAY_TIME_LEVELS 10.0
#define THREAD_NUM 3

void * phrd_func(void *arg)

void * thrd_ret;
int count=0;
int delay_time=0;
int thread_num=(int)arg;
printf("thread %d is starting\n");
for(count=0;count<REPEAT_NUM;++count)

delay_time=(int)(rand()*DELAY_TIME_LEVELS/(RAND_MAX))+1;
sleep(delay_time);
printf("thread %d :iob %d : delay %ds\n",thread_num,count,delay_time);

printf("thread %d finishde\n",thread_num);
pthread_exit(NULL);

int main()

void * thrd_ret;
pthread_t thread[THREAD_NUM];
int no,ret;
srand(time(NULL));
for(no=0;no<THREAD_NUM;++no)

ret=pthread_create(&thread[no],NULL,phrd_func,(void *)no);
if(ret!=0)

printf("error pthresd\n");
exit(ret);


printf("creat threads sucess : waiting threads finished\n");
for(no=0;no<THREAD_NUM;no++)

ret=pthread_join(thread[no],&thrd_ret);
if(!ret)

printf("thread %d joined\n",no);

else

printf("thread %d joined failed\n",no);


return 0;

编译报告如下
[lyc@localhost lyc]$ gcc a.c
/tmp/cco2MhOv.o(.text+0x108): In function `main':
: undefined reference to `pthread_create'
/tmp/cco2MhOv.o(.text+0x168): In function `main':
: undefined reference to `pthread_join'
collect2: ld returned 1 exit status
pthread.h如下：
/* Function for handling threads. */

/* Create a thread with given attributes ATTR (or default attributes
if ATTR is NULL), and call function START_ROUTINE with given
arguments ARG. */
extern int pthread_create (pthread_t *__restrict __threadp,
__const pthread_attr_t *__restrict __attr,
void *(*__start_routine) (void *),
void *__restrict __arg) __THROW;
/* Terminate calling thread. */
extern void pthread_exit (void *__retval)
__THROW __attribute__ ((__noreturn__));

/* Make calling thread wait for termination of the thread TH. The
exit status of the thread is stored in *THREAD_RETURN, if THREAD_RETURN
is not NULL. */
extern int pthread_join (pthread_t __th, void **__thread_return) __THROW;
求高手解答

参考技术A 原因：
头文件 pthread.h 没有包含到源文件中
解决方法：
1）将 pthread.h 复制到源文件相同的文件夹中
2）修改为：#include "pthread.h"追问

我这样尝试了，但还是不行

追答

也许pthread.h 文件本身有问题了

参考技术B 添加编译选项-lpthread，因为pthread不是标准的编译链接的库，需要自己添加 参考技术C 你编译 a.c 怎么涉及到 cco2MhOv.o 或 cco2MhOv.c ?

头文件除了 #include <pthread.h>
是否还要 #include <sys/types.h>本回答被提问者和网友采纳