[英]Regarding macros
may i know what is the problem in using the below x-macro code 我可以知道使用下面的x宏代码有什么问题吗
#define FILL_BUFF_1 (int *)(0x01, 0x02)
#define FILL_BUFF_2 (int *)(0x03, 0x04)
#define X(a,b)
#define LOOK_UP \
X(0x13, FILL_BUFF_1), \
X(0x14, FILL_BUFF_2)
#undef X
#define X(a,b) a
int pid_table[2] = {LOOK_UP};
#undef X
#define X(a,b) b
int *pid_buff_ptr[2] = {LOOK_UP};
void main(int argc, _TCHAR* argv[])
{
printf("%d ", (pid_buff_ptr+0)); // displays 0x02
printf("%d ", (pid_buff_ptr+1)); // displays 0x04
printf("%d " ,*(pid_buff_ptr[0] + 1)); // doesnt work
}
How can I make the above code to access other elements in the buffer? 如何使上面的代码访问缓冲区中的其他元素?
(Taking a wild stab at this just because it's been sitting here a while unanswered.) (对此采取狂野的攻击只是因为它已经坐在这里好一阵子了,没有人回答。)
In the last line, you appear to be dereferencing the value 0x03 as a pointer -- I suspect you are getting a SIGSEGV? 在最后一行中,您似乎将值0x03取消引用作为指针-我怀疑您正在获取SIGSEGV?
pid_buff_ptr[0] == 0x02
so 所以
(pid_buff_ptr[0] + 1) == 0x03
so 所以
*(pid_buff_ptr[0] + 1)
is dereferencing 0x03 as a pointer. 正在取消引用0x03作为指针。
I am not sure what exactly you're trying to do, but if I guessed correctly, you want to have the pid_buff_ptr
variable contain an array of int
values, not an array of int *
values. 我不确定您到底想做什么,但是如果我猜对了,您想让pid_buff_ptr
变量包含一个int
值数组,而不是一个int *
值数组。
If that is the case, you need to change 如果是这种情况,您需要进行更改
#define FILL_BUFF_1 (int *)(0x01, 0x02)
#define FILL_BUFF_2 (int *)(0x03, 0x04)
to 至
#define FILL_BUFF_1 {0x01, 0x02}
#define FILL_BUFF_2 {0x03, 0x04}
Change the following: 更改以下内容:
int *pid_buff_ptr[2] = {LOOK_UP};
to 至
int pid_buff_ptr[][2] = {LOOK_UP};
To print, you would use something like: 要进行打印,您将使用类似:
printf("%d ", pid_buff_ptr[0][1]);
Of course, I could be wrong. 当然,我可能是错的。
Now, some other comments: 现在,其他一些评论:
#include <stdio.h>
before using printf()
. 使用printf()
之前,您需要#include <stdio.h>
。 main()
returns int
. main()
返回int
。 main()
returns int
, you should return an int
from it. 由于main()
返回int
,因此您应该从中返回一个int
。 Traditionally, 0
means success. 传统上, 0
表示成功。 _TCHAR
is, but if it is not an alias or #define
for char
, you might be in trouble. 我不知道_TCHAR
是什么,但是如果它不是char
的别名或#define
,则可能会遇到麻烦。 Even with the above changes, I don't understand the need to do the trickery with the pre-processor. 即使进行了上述更改,我也不了解使用预处理器进行欺骗的必要性。 What exactly are you trying to do? 您到底想做什么?
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