ether_ntoa指针转换问题
我正在尝试使用 ether_ntoa 打印 MAC 地址。当我尝试这样做时
printf("MAC (src): %s\n",ether_ntoa((struct ether_addr *)&eheader->ether_shost));
，我遇到了分段错误，所以我想出了两种不同的方法：
这是代码片段n°1：
struct ether_header *eheader;
char *p;
...
p = ether_ntoa(struct ether_addr *) &eheader->ether_shost);
printf("-MAC (src): %s\n",p);
我得到的警告是：
赋值使指针来自 整数不带强制转换
，所以我进行强制转换并且......
这是代码片段n°2：
struct ether_header *eheader;
char *p;
...
p = (char *) ether_ntoa((struct ether_addr *) &eheader->ether_shost);
printf("-MAC (src): %s\n",p);
我得到的警告是：
从整数转换为指针 尺寸不同
如果你看一下手册页，ether_ntoa 是这样定义的，返回一个 char *:
extern char *ether_ntoa (__const struct ether_addr *__addr) __THROW;
所以我不知道我做错了什么。问题是“不是”警告，而是当我尝试打印它时出现的分段错误。
我在 openSUSE 下遇到这个错误（在 ubuntu 中我不需要做这个 *p 技巧），所以如果这里有 openSUSE 专家，我将感谢她的帮助。
非常感谢！
I am trying to print the MAC address by using ether_ntoa. When i try to do
printf("MAC (src): %s\n",ether_ntoa((struct ether_addr *)&eheader->ether_shost));
I get a segmentation fault, so I have come up with two different approaches:
This is the snippet code nº1:
struct ether_header *eheader;
char *p;
...
p = ether_ntoa(struct ether_addr *) &eheader->ether_shost);
printf("-MAC (src): %s\n",p);
and the warning I obtain is:
assignment makes pointer from
integer without a cast
so I do the cast and ...
This is the snippet code nº2:
struct ether_header *eheader;
char *p;
...
p = (char *) ether_ntoa((struct ether_addr *) &eheader->ether_shost);
printf("-MAC (src): %s\n",p);
and the warning I obtain is:
cast to pointer from integer of
different size
If you take a look at the man page, ether_ntoa is defined this way, returning a char *:
extern char *ether_ntoa (__const struct ether_addr *__addr) __THROW;
so I don't know what I am doing wrong. The problem is "not" the warning, is the segmentation fault it comes after, when I try to print it.
I am getting this error under openSUSE (in ubuntu I don't need to do this *p trick) so if there is an openSUSE expert here I will appreciate her help.
Thank you very much!
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此警告：
...并不是添加演员的邀请。它告诉你一个更严重的问题；在这种情况下，编译器认为
ether_ntoa()返回一个int。当您使用作用域内没有声明的函数时，就会发生这种情况；对于这样的库函数，这意味着您没有包含正确的标头。对于
ether_ntoa()，您需要#include。This warning:
...is not an invitation to add a cast. It's telling you about a more serious problem; in this case, that the compiler thinks
ether_ntoa()returns anint.This happens when you use a function without a declaration in scope; for a library function like this, it means that you haven't included the right header. For
ether_ntoa(), you need#include <netinet/ether.h>.这听起来确实像是标头/库和编译器之间的字大小不匹配。您的 Suse 机器上是否有一些奇怪的 64 位和 32 位环境混合？
That sure sounds like a word-size mismatch between the headers/library and the compiler. Do you have some strange mix of 64-bit and 32-bit environment in that Suse machine?
这是一个图书馆问题。我不知道我怎么没有检查这一点（也许是因为这是老师提供的文件，其中包含所需的所有库）。
执行 include:
是解决方案，所以我认为问题已得到解答。
非常感谢你们俩。
It was a library problem. I don't know how I didn't check that (maybe because it was a file provided by the teacher with all the libraries needed ¬¬).
Doing the include:
was the solution, so I consider the question answered.
Thank you very much to both of you.