编译器指令不起作用 [英] Compiler Directives Not Working
问题描述
在VS 2003中工作。
头文件中的
：
[test.h]
#ifdef _UNUSED_NAME_3223458 //这个在任何时候都没有定义
#define TEST123 6789
#endif
实现文件中的
：
[test.cpp]
\\ TEST123的值将是6789或分配给它的任何值
即使_UNUSED_NAME_3223458从未定义且不存在
in any other文件。
[\ test.cpp]
另外，如果你这样做：
#ifndef _UNUSED_NAME_3223458
#define TEST123 0
#endif
在另一个之前插入此项（因此您在<之前测试未定义
定义），TEST123的值为0而不是6789.
没有错误或警告。
这几乎就像你测试的变量一样（_UNUSED_NAME_3223458
是从来没有在任何时候定义过）当你在测试它的时候处于未知状态。
这里发生了什么？
Working in VS 2003.
in a header file:
[test.h]
#ifdef _UNUSED_NAME_3223458 //this is not defined anywhere at anytime
#define TEST123 6789
#endif
[\test.h]
in the implementation file:
[test.cpp]
\\the value of TEST123 will be 6789 or whatever value is assigned to it
even though _UNUSED_NAME_3223458 was never defined and is not present
in any other files.
[\test.cpp]
Also, if you do:
#ifndef _UNUSED_NAME_3223458
#define TEST123 0
#endif
Insert this prior to the other one(so you test for not defined before
defined), TEST123 will have a value of 0 and not 6789.
No errors or warnings.
It is almost as if the variable you testing( _UNUSED_NAME_3223458 which
is never defined at any time) is in an unknown state at the time you
test it.
What is going on here?
推荐答案
sh ***** ******@gmail.com 写道：
在VS 2003中工作。
也许你应该问''微软。 public.vc.language''...
在一个头文件中：
[test.h]
#ifdef _UNUSED_NAME_3223458 //这个在任何时候都没有定义
#define TEST123 6789
#endif
在实现文件中：
[test.cpp]
\\ TEST123的值将是6789或分配给它的任何值
即使_UNUSED_NAME_3223458从未定义过，也不是在任何其他文件中呈现
。
通过_definition_如果''TEST123'具有值6789（或其他），则意味着
''TEST123''被定义_elsewhere_ *以及*这里，或者
" _UNUSED_NAME_3223458"宏实际上是_defined_，这就是C ++
预处理器如何定义''TEST123'。
你想要怀疑的是什么这是
预处理器的基本功能。我是_sure_这是你犯了错误的人。你确定
它是'ifdef"而不是ifndef？...
[\ test.cpp]
如果你这样做：
＃ifnf _UNUSED_NAME_3223458
#define TEST123 0
#endif
在另一个之前插入此项（因此在
定义之前测试未定义），TEST123的值为0而不是6789 。
没有错误或警告。
几乎就像你测试的变量（_UNUSED_NAME_3223458，
从未在任何时间定义）处于未知状态当时你要测试它。
这里发生了什么？
Working in VS 2003.
Perhaps you should ask in ''microsoft.public.vc.language''...
in a header file:
[test.h]
#ifdef _UNUSED_NAME_3223458 //this is not defined anywhere at anytime
#define TEST123 6789
#endif
[\test.h]
in the implementation file:
[test.cpp]
\\the value of TEST123 will be 6789 or whatever value is assigned to it
even though _UNUSED_NAME_3223458 was never defined and is not present
in any other files.
By _definition_ if ''TEST123'' has the value 6789 (or whatever), it means
that either ''TEST123'' is defined _elsewhere_ *as well* as here, or that
"_UNUSED_NAME_3223458" macro is in fact _defined_ and that''s how the C++
preprocessor knows to define ''TEST123".
What you''re trying to doubt here is the very basic functionality of the
preprocessor. I am _sure_ it''s you who''s made the mistake. Are you sure
it''s "ifdef" and not "ifndef"?...
[\test.cpp]
Also, if you do:
#ifndef _UNUSED_NAME_3223458
#define TEST123 0
#endif
Insert this prior to the other one(so you test for not defined before
defined), TEST123 will have a value of 0 and not 6789.
No errors or warnings.
It is almost as if the variable you testing( _UNUSED_NAME_3223458 which
is never defined at any time) is in an unknown state at the time you
test it.
What is going on here?
无法说出来。你的代码片段没有足够的信息。
你要求从这些片段到概念的一个相当大的飞跃
其他一切都没问题，你没有不知怎的，搞砸了。我宁愿
相信编译器。
V
-
请删除资本来自我在邮寄回复时的地址
Impossible to say. Your code fragments do not carry enough information.
You''re asking for a rather big leap from those fragments to the notion
that everything else is OK, and you didn''t screw up somehow. I''d rather
believe the compiler.
V
--
Please remove capital As from my address when replying by mail
sh ***********@gmail.com 写道：
在VS 2003中工作。
在头文件中：
[test.h]
＃ifdef _UNUSED_NAME_3223458 //这在任何时候都没有定义
_UNUSED_NAME_3223458保留给实现。您不能在代码中使用
。
#define TEST123 6789
#endif
Working in VS 2003.
in a header file:
[test.h]
#ifdef _UNUSED_NAME_3223458 //this is not defined anywhere at anytime
_UNUSED_NAME_3223458 is reserved to the implementation. You can''t use
it in your code.
#define TEST123 6789
#endif
2006年2月8日星期三09:00:48 -0800，shane.tietjen写道：
On Wed, 08 Feb 2006 09:00:48 -0800, shane.tietjen wrote:
在VS 2003工作。
在头文件中：
[test.h]
＃ifdef _UNUSED_NAME_3223458 //这在任何时候都没有定义
#define TEST123 6789
#endif
[\ test.h]
在实施文件中：
[test.cpp]
\\ TEST123的值将是6789或分配给它的任何值
即使_UNUSED_NAME_3223458从未被定义且在任何其他文件中不存在
。
Working in VS 2003.
in a header file:
[test.h]
#ifdef _UNUSED_NAME_3223458 //this is not defined anywhere at anytime
#define TEST123 6789
#endif
[\test.h]
in the implementation file:
[test.cpp]
\\the value of TEST123 will be 6789 or whatever value is assigned to it
even though _UNUSED_NAME_3223458 was never defined and is not present
in any other files.
在test.h中的#ifdef之前放入
#undef _UNUSED_NAME_3223458
如果修复它，那么
_UNUSED_NAME_3223458定义*某处*。 （预处理器可能在
项目设置中定义了吗？）
此外，如果将其更改为
怎么办？ #ifdef _UNUSED_NAME_3223458foo
？它的行为是否仍然相同？
- Jay
Put
#undef _UNUSED_NAME_3223458
right before the #ifdef in test.h. If that fixes it, then
_UNUSED_NAME_3223458 is defined *somewhere*. (Preprocessor defines in the
project settings perhaps?)
Also, what if you change it to
#ifdef _UNUSED_NAME_3223458foo
? Does it still behave the same?
- Jay
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