3

我正在尝试使用 gcc -Wall -std=c99 hilo.c - ./a.out hilo.c 运行这个 C 程序，我收到以下错误消息：

hilo.c: In function ‘func’:
hilo.c:6:3: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘pthread_t’ [-Wformat]
hilo.c: In function ‘main’:
hilo.c:14:3: warning: passing argument 3 of ‘pthread_create’ from incompatible pointer type [enabled by default]
/usr/include/pthread.h:225:12: note: expected ‘void * (*)(void *)’ but argument is of type ‘void (*)(void)’
hilo.c:15:3: warning: passing argument 3 of ‘pthread_create’ from incompatible pointer type [enabled by default]
/usr/include/pthread.h:225:12: note: expected ‘void * (*)(void *)’ but argument is of type ‘void (*)(void)’
hilo.c:24:3: warning: statement with no effect [-Wunused-value]
/tmp/cchmI5wr.o: In function `main':
hilo.c:(.text+0x52): undefined reference to `pthread_create'
hilo.c:(.text+0x77): undefined reference to `pthread_create'
hilo.c:(.text+0x97): undefined reference to `pthread_join'
hilo.c:(.text+0xab): undefined reference to `pthread_join'
collect2: ld returned 1 exit status

不知道代码有什么问题，所以如果有人可以帮助我，将不胜感激。

这是代码：

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

void func(void){

         printf("thread %d\n", pthread_self());
         pthread_exit(0);

}

   int main(void){

        pthread_t hilo1, hilo2;

        pthread_create(&hilo1,NULL, func, NULL);
        pthread_create(&hilo2,NULL, func, NULL);

        printf("the main thread continues with its execution\n");

        pthread_join(hilo1,NULL);
        pthread_join(hilo2, NULL);

        printf("the main thread finished");

        scanf;

  return(0);

}
4

3 回答 3

8

您应该编译并链接到-pthread.

gcc -Wall -std=c99 hilo.c -pthread

使用是不够的-lpthread。该-pthread标志将改变一些 libc 函数的工作方式，以使它们在多线程环境中正常工作。

于 2013-03-23T23:59:58.347 回答
5

您尚未链接 pthread 库。编译：

gcc -Wall -std=c99 hilo.c -lpthread
于 2013-03-23T23:55:30.780 回答
2

改变

void func(void)

至

void* func(void *)

并编译

gcc hilo.c -pthread

您只会在打印时出错，pthread_self()因为它不是int.

于 2013-12-12T07:11:23.260 回答