Linux 中对 pthread_create 的未定义引用 [英] Undefined reference to pthread_create in Linux
问题描述
我从 https://computing.llnl.gov/tutorials 从网上获取了以下演示/pthreads/
#include <pthread.h>
#include <stdio.h>
#define NUM_THREADS 5
void *PrintHello(void *threadid)
{
long tid;
tid = (long)threadid;
printf("Hello World! It's me, thread #%ld!
", tid);
pthread_exit(NULL);
}
int main (int argc, char *argv[])
{
pthread_t threads[NUM_THREADS];
int rc;
long t;
for(t=0; t<NUM_THREADS; t++){
printf("In main: creating thread %ld
", t);
rc = pthread_create(&threads[t], NULL, PrintHello, (void *)t);
if (rc){
printf("ERROR; return code from pthread_create() is %d
", rc);
exit(-1);
}
}
pthread_exit(NULL);
}
但是当我在我的机器上编译它(运行 Ubuntu Linux 9.04)时,我收到以下错误:
But when I compile it on my machine (running Ubuntu Linux 9.04) I get the following error:
corey@ubuntu:~/demo$ gcc -o term term.c
term.c: In function ‘main’:
term.c:23: warning: incompatible implicit declaration of built-in function ‘exit’
/tmp/cc8BMzwx.o: In function `main':
term.c:(.text+0x82): undefined reference to `pthread_create'
collect2: ld returned 1 exit status
这对我来说没有任何意义,因为标头包含 pthread.h
,它应该具有 pthread_create
函数.有什么想法吗?
This doesn't make any sense to me, because the header includes pthread.h
, which should have the pthread_create
function. Any ideas what's going wrong?
推荐答案
对于 Linux,正确的命令是:
For Linux the correct command is:
gcc -pthread -o term term.c
一般来说,库应该遵循命令行上的源和对象,而 -lpthread
不是一个选项",它是一个库规范.在仅安装了 libpthread.a
的系统上,
In general, libraries should follow sources and objects on command line, and -lpthread
is not an "option", it's a library specification. On a system with only libpthread.a
installed,
gcc -lpthread ...
将无法链接.
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