帮助__cplusplus [英] Help with __cplusplus
问题描述
Hello Netlanders，我开始学习''C''语言
并阅读一些代码我找到了这段代码：
＃ ifdef __cplusplus
externC {
#endif
是否有人可以向我解释这段代码，因为
我看到这个__ cplusplus ;和外部C和 {"看看C和C ++之间的区别是一种
标准，但我不确定
我想要更多信息......
如果你知道这些东西或有关阅读的信息请
让我知道。
Hello Netlanders, I''m starting to learn the ''C'' language
and reading some code I found this code:
#ifdef __cplusplus
extern "C" {
#endif
Is there someone who could explain me about this code, because
I see that this "__cplusplus" and "extern "C" {" is a kind of
standard to see the difference between C and C++, but I''m not sure
and I want more Information ...
If you know about this stuff or about a reading to consult please
let me know it.
推荐答案
Arturo写道：
Arturo writes:
我开始学习''C''语言
并阅读一些代码我找到了这段代码：
#ifdef __cplusplus
externC {
#endif
是否有人可以向我解释这段代码，因为
我看到这个__ cplusplus和外部C和 {"是一种看待C和C ++之间差异的标准，但我不确定
我想要更多信息...
如果你知道这个请给我一些阅读材料。
让我知道。
I''m starting to learn the ''C'' language
and reading some code I found this code:
#ifdef __cplusplus
extern "C" {
#endif
Is there someone who could explain me about this code, because
I see that this "__cplusplus" and "extern "C" {" is a kind of
standard to see the difference between C and C++, but I''m not sure
and I want more Information ...
If you know about this stuff or about a reading to consult please
let me know it.
看起来您遇到了库函数的标题和
供应编译器的供应商对C ++编译器使用相同的库。
这是常态，如今。 __cplusplus意味着*你的*编译器
（它不能代表C标准中的任何内容，因为时间似乎仅在前向方向上流入
而在C ++之前是C ）。语法externC。 {是一种方式
来击败名称错误，C ++有一个属性而C没有。
我可能错了但我的猜测是你正在服用
学习的错误方法;当你遇到
时，试图吸收并让一切都有意义。这些新闻组中的很多人都含蓄地提倡这一点，但是我个人，毕竟我的运气非常糟糕，学习*任何东西*
方式。先熟悉编写简单的程序，然后再回去，
填补你知识的漏洞。有些人称之为螺旋式或
螺旋式方法。在你最终吸收之前可能需要多次重访
all - 在C ++的情况下你可能会先死掉。
查看标题不是新手学习任何东西的好方法
除了计算机编程是一项复杂的业务。
It looks like you have encountered the header of a library function and the
vendor that supplies the compiler uses the same library for a C++ compiler.
This is the norm, nowadays. __cplusplus means something to *your* compiler
(it can''t mean anything in the C standard because time only seems to flow in
the forward direction and C preceded C++). The syntax extern"C" { is a way
to defeat name mangling, a property that C++ has and C does not.
I could be wrong but my guess is you are taking the wrong approach to
learning; trying to absorb and have everything make sense as you encounter
it. A great many people on these newsgroups implicitly advocate that but I,
personally, have had very poor luck my entire life learning *anything* that
way. Get fairly fluent in writing simple programs first, then go back and
fill in the holes in your knowledge. What some people call a spiral or
helical approach. It may take several revisits before you finally absorb it
all - in the case of C++ you may very well die first.
Looking at headers is not a good way for a novice to learn much of anything
except that computer programming is a complex business.
例如****** @ yahoo.com.mx （Arturo）写道：
eg******@yahoo.com.mx (Arturo) wrote:
Hello Netlanders，I''我开始学习'''C语言
并阅读一些代码我发现这段代码：
#ifdef __cplusplus
extern" C" {
#endif
是否有人可以向我解释这段代码，因为
我看到这个__ cplusplus和外部C和 {"是一种看C和C ++之间区别的标准，但我不确定
我想要更多信息...
[火焰屏蔽：警告，部分OT]
__cplusplus是一个宏，C实现*不允许在标准符合模式下定义
。它通常由
C ++编译器定义。外部C表示外部C。 part告诉C ++编译器，
以下代码需要C调用约定。 （请注意：进一步
关于C ++的问题应该转到comp.lang.c ++以避免
烦恼。）
如果你知道的话这个东西或关于阅读请咨询
让我知道。
Hello Netlanders, I''m starting to learn the ''C'' language
and reading some code I found this code:
#ifdef __cplusplus
extern "C" {
#endif
Is there someone who could explain me about this code, because
I see that this "__cplusplus" and "extern "C" {" is a kind of
standard to see the difference between C and C++, but I''m not sure
and I want more Information ...
[flame-shield: warning, partially OT]
__cplusplus is a macro that a C implementation is *not* allowed to
define in standard conforming mode. It''s conventionally defined by
C++ compilers. The extern "C" part tells a C++ compiler, that the
following code requires C calling conventions. (Please note: further
questions about C++ should be directed to comp.lang.c++ to avoid
irritations.)
If you know about this stuff or about a reading to consult please
let me know it.
你肯定想阅读_C编程语言_由Kernighan
和Ritchie，第二版（K& R2），伴随着comp.lang.c-FAQ
（签名链接）。顺便说一句，常见问题解答在第18.10节提供了一些更好的书
建议。
祝你好运！
问候
-
Irrwahn Grausewitz（ir*******@freenet.de）
欢迎来到clc： http://www.ungerhu.com/jxh/clc.welcome.txt
clc faq-list： http ：//www.faqs.org/faqs/C-faq/faq/
clc OT指南： http://benpfaff.org/writings/clc/off-topic.html
You definitely want to read _The C Programming Language_ by Kernighan
and Ritchie, second edition (K&R2), accompanied by the comp.lang.c-FAQ
(link in signature). BTW, the FAQ provides some more good book
recommendations in section 18.10.
Good luck!
Regards
--
Irrwahn Grausewitz (ir*******@freenet.de)
welcome to clc: http://www.ungerhu.com/jxh/clc.welcome.txt
clc faq-list : http://www.faqs.org/faqs/C-faq/faq/
clc OT guide : http://benpfaff.org/writings/clc/off-topic.html
2004年6月9日星期三，Arturo写道：
On Wed, 9 Jun 2004, Arturo wrote:
Hello Netlanders，我开始学习''C''语言
并阅读一些代码我找到了这段代码：
#ifdef __cplusplus
externC {
#endif
是否有人可以向我解释这段代码，因为
我看到这个__ cplusplus和外部C和 {"是一种看待C和C ++之间差异的标准，但我不确定
我想要更多信息...
如果你知道这个请参考或者阅读请参阅
让我知道。
Hello Netlanders, I''m starting to learn the ''C'' language
and reading some code I found this code:
#ifdef __cplusplus
extern "C" {
#endif
Is there someone who could explain me about this code, because
I see that this "__cplusplus" and "extern "C" {" is a kind of
standard to see the difference between C and C++, but I''m not sure
and I want more Information ...
If you know about this stuff or about a reading to consult please
let me know it.
这是C ++的一个功能。您正在查看的代码是为作为C或C ++编译器的
编译器而设计的。如果为C
设置开关，则#ifdef为false并使用extern。如果设置开关为
C ++，则#ifdef为true，并且它根据C ++的要求使用extern。如果你对b $ b感兴趣，请向comp.lang.c ++中的人询问
''extern" C"''是关于或查看一个关于C ++的书。
-
发送电子邮件至：darrell at cs dot toronto dot edu
Don''发送电子邮件至 vi ************ @ whitehouse.gov
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