为什么我会和QUOT;未定义的引用＆QUOT;错误甚至当我有正确的头文件？ [英] Why do I get "undefined reference" errors even when I include the right header files?

问题描述

当我试图编译这个程序，它失败：

When I tried to compile this program, it failed:

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>

void *WriteNumbers(void *threadArg)
{
    int start, stop;

    start = atoi((char *)threadArg);
    stop = start + 10;

    while (start < stop)
    {
         printf("%d\n", start++);
         sleep(1);
    }
    return 0;
}

int main(int argc, char **argv)
{
        pthread_t thread1, thread2;

        // create the threads and start the printing
        pthread_create(&thread1, NULL, WriteNumbers, (void *)argv[1] );
        pthread_create(&thread2, NULL, WriteNumbers, (void *)argv[2]);

        pthread_join(thread1, NULL);
        pthread_join(thread2, NULL);

        return 0;
}

它给了我以下错误：

It gave me the following errors:

tmp/ccrW21s7.o: In function `main':
pthread.c:(.text+0x83): undefined reference to `pthread_create'
pthread.c:(.text+0xaa): undefined reference to `pthread_create'
pthread.c:(.text+0xbd): undefined reference to `pthread_join'
pthread.c:(.text+0xd0): undefined reference to `pthread_join'
collect2: ld returned 1 exit status

为什么它给我的，即使我已经包括 pthreads.h中，其中声明这些功能，这些未定义的引用错误？

Why does it give me these undefined reference errors even though I had included pthread.h, which declares these functions?

推荐答案

您可能忘记与pthreads库链接（使用 -lpthread 在命令行上）。

You probably forgot to link with the Pthreads library (using -lpthread on the command line).

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