Linux下undefined reference to ‘pthread_create’问题解决 zz

接触了Linux系统编程中的线程编程模块，可gcc sample.c（习惯把书上的sample代码写进sample.c文件中）出现“undefined reference to ‘pthread_create’”，所有关于线程的函数都会有此错误，导致无法编译通过。

问题的原因：pthread不是Linux下的默认的库，也就是在链接的时候，无法找到phread库中哥函数的入口地址，于是链接会失败。

解决：在gcc编译的时候，附加要加 -lpthread参数即可解决。

#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
pthread_t ntid;
void printids(const char * s)
{
    pid_t pid;
    pthread_t tid;
    pid = getpid();
    tid = pthread_self();
    printf("%s pid %u tid %u (0x%x)\n",s,(unsigned int)pid,
            (unsigned int)tid,(unsigned int)tid);
}
void * thr_fn(void * arg)
{
    printids("new thread:");
    return ((void *)0);
}
int main(void)
{
    int err;
    err = pthread_create(&ntid,NULL,thr_fn,NULL);
    if(err != 0)
        printf("pthread_create error \n");
    printids("main thread:");
    sleep(1);
    return 0;
}

root@daoluan:/code/pthreadid# gcc sample.c
/tmp/cc1WztL9.o: In function `main’:
sample.c:(.text+0×83): undefined reference to `pthread_create’
collect2: ld returned 1 exit status

root@daoluan:/code/pthreadid# gcc -lpthread sample.c
root@daoluan:/code/pthreadid# ./a.out
main thread: pid 7059 tid 3078141632 (0xb778b6c0)
new thread: pid 7059 tid 3078138736 (0xb778ab70)