undefined reference to `pthread_create' in Linux

undefined reference to `pthread_create' in Linux

情况说明

在进行Linux系统多线程编程学习时，使用了 pthread_create这一系统调用。但是在使用gcc编译时出现了报错，具体如下：

代码：

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
/* this data is shared by the threads */
int sum;
/* threads call this function */
void *runner(void *param);

int main(int argc, char *argv[])
{
    pthread_t tid;
    pthread_attr_t attr;
    if (argc != 2){
        fprintf(stderr, "usage: a.out <integer value>\n");
        return -1;
    }
    if (atoi(argv[1]) < 0){
        fprintf(stderr, "%d must be >= 0\n", atoi(argv[1]));
        return -1;
    }
    /* get default attributes */
    pthread_attr_init(&attr);
    /* create the thread */
    pthread_create(&tid, &attr, runner, argv[1]);
    /* wait for the thread to exit */
    pthread_join(tid, NULL);

    printf("the sum is %d\n", sum);
    return 0;
}

void *runner(void *param){
    int i, upper = atoi(param);
    sum = 0;
    for(i = 0; i <= upper; i++){
        sum += i;
    }
    pthread_exit(0);
}

报错：

/usr/bin/ld: /tmp/ccAmXOUU.o: in function `main':
4-9-pthreads.c:(.text+0xcd): undefined reference to `pthread_create'
/usr/bin/ld: 4-9-pthreads.c:(.text+0xde): undefined reference to `pthread_join'
collect2: error: ld returned 1 exit status

解决办法

在编译时，加上所需要的库，即 pthread

gcc -o test test.c -pthread

参考文章

https://stackoverflow.com/questions/1662909/undefined-reference-to-pthread-create-in-linux