在编译时宏中增加一个数字 [英] Increment a number in compile time macro
问题描述
开关（i）{
案例1：
休息;
案例2：
休息;
[...]
案例N：
休息;
}
现在，经过一段时间我想在案例1和案例
2之间添加一个案例2，结果意味着案例2之后的每个案例编号都需要将
增加1，它有一个宏观技巧让生活更轻松吗？这样的
为：
开关（i）{
案例AUTO_INC_MACRO：
休息;
案例AUTO_INC_MACRO：
....
提前致谢。
Bin
switch(i) {
case 1:
break;
case 2:
break;
[...]
case N:
break;
}
Now, after some time I want to add a ''case 2'' between case 1 and case
2, the result means every case number after case 2 need to be
incremented by 1, it there a macro tricks to make life easier? Such
as:
switch(i) {
case AUTO_INC_MACRO:
break;
case AUTO_INC_MACRO:
....
Thanks in advance.
Bin
推荐答案
Bin Chen写道：
Bin Chen wrote:
switch（i）{
案例1：
休息;
案例2：
休息;
[.. 。]
案例N：
休息;
}
现在，一段时间后我想在案例1和案例
2之间添加案例2，结果意味着案例2之后的每个案例编号都需要增加
1，它有一个宏观技巧，让生活更轻松？这样的
as：
switch(i) {
case 1:
break;
case 2:
break;
[...]
case N:
break;
}
Now, after some time I want to add a ''case 2'' between case 1 and case
2, the result means every case number after case 2 need to be
incremented by 1, it there a macro tricks to make life easier? Such
as:
使用枚举。永远不要使用魔法数字。
-
Ian Collins。
Use an enum. Never use magic numbers.
--
Ian Collins.
陈斌说：
Bin Chen said:
switch（i）{
案例1：
休息;
案例2：
休息;
[...]
案例N：
休息;
}
现在，经过一段时间我想在案例1和案例之间添加一个案例2
2，结果意味着案例2之后的每个案例编号都需要增加1，它有一个宏观技巧让生活更轻松吗？这样的
为：
开关（i）{
案例AUTO_INC_MACRO：
休息;
案例AUTO_INC_MACRO：
...
switch(i) {
case 1:
break;
case 2:
break;
[...]
case N:
break;
}
Now, after some time I want to add a ''case 2'' between case 1 and case
2, the result means every case number after case 2 need to be
incremented by 1, it there a macro tricks to make life easier? Such
as:
switch(i) {
case AUTO_INC_MACRO:
break;
case AUTO_INC_MACRO:
...
我扫描了伊恩的回答（使用枚举确实！哦，亲爱的我......），
我立刻想到了自己，哦，我觉得我能做得更好
比那个 - Ian'a chap chap chap chap but but but but but but but but but but but $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ b真正的C黑客，是吗？然后，正确的是，我通过适当的方式阅读了问题
，这样我就可以通过提供最好的建议和最多来展示我惊人的巫术C技能
有用的洞察力。
所以 - 你准备好了我惊人的智慧之珠吗？好。请仔细聆听
，然后...
使用枚举。
-
Richard Heathfield< http://www.cpax.org.uk>
电子邮件：-http：// www。 + rjh @
谷歌用户：< http://www.cpax.org.uk/prg/writings/googly.php>
Usenet是一个奇怪的放置" - dmr 1999年7月29日
I scanned Ian''s answer ("Use an enum", indeed! Ohhhhhh deary deary me...),
and I immediately thought to myself, "oh, I reckon I can do a lot better
than that - Ian''s a nice enough chap but he''s really a C++ guy at heart,
and he doesn''t understand all the subtle and clever options available to
the real C hacker, does he?" Then, as is only proper, I read the question
through properly, so that I could show off my astounding wizardly C skills
by giving the best possible advice and the most helpful possible insight.
So - are you ready for my astounding pearl of wisdom? Good. Listen
carefully, then...
Use an enum.
--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999
2008年9月6日星期六23:54:08 -0700（PDT），陈斌
< bi *********@gmail.com写道：
On Sat, 6 Sep 2008 23:54:08 -0700 (PDT), Bin Chen
<bi*********@gmail.comwrote:
> switch（i）{
案例1：
休息;
案例2：
休息;
[...]
案例N：
休息;
}
现在，经过一段时间我想在案例1和案例
2之间添加一个案例2，结果意味着案例2之后的每个案例编号需要增加1，它有一个宏观技巧，让生活更轻松？如下：
开关（i）{
案例AUTO_INC_MACRO：
休息;
案例AUTO_INC_MACRO：
>switch(i) {
case 1:
break;
case 2:
break;
[...]
case N:
break;
}
Now, after some time I want to add a ''case 2'' between case 1 and case
2, the result means every case number after case 2 need to be
incremented by 1, it there a macro tricks to make life easier? Such
as:
switch(i) {
case AUTO_INC_MACRO:
break;
case AUTO_INC_MACRO:
宏不执行计算。他们只执行文字
替换。然后在代码中随后出现一个宏
将无法访问先前出现的结果。
然而，你可以做你想做的事情用枚举。形式的东西
enum {CASE1 = 1，CASE2，...，CASEN};
并将每个案例标签更改为
case CASE1：
...
案例CASE2：
等
后来，当你想在CASE1和CASE2之间插入一个案例，更改
你枚举为
enum {CASE1 = 1，CASE1A，CASE2，...，CASEN};
并在CASE2标签之前插入新的代码块。
在六次插入后消除猖獗的混乱
CASE6可能是7而CASE10是13，我建议使用标识符
，它们暗示要执行的功能而不是它们的
数值。比如
enum {INSERT = 1，DELETE，EDIT，COMPUTE};
然后你可以将它修改为
enum {INSERT = 1，删除，编辑，打印，计算};
-
删除电子邮件的del
Macros don''t perform calculations. They only perform text
substitution. And a subsequent appearance of a macro in your code
will not have access to the result of a previous appearance.
However, you can do what you want with an enum. Something of the form
enum {CASE1=1, CASE2, ..., CASEN};
and change each case label to
case CASE1:
...
case CASE2:
etc.
Later, when you want to insert a case between CASE1 and CASE2, change
you enum to
enum {CASE1=1, CASE1A, CASE2, ..., CASEN};
and insert the new block of code immediately before the CASE2 label.
To eliminate the rampant confusion after a half-dozen insertions where
CASE6 may be 7 while CASE10 is 13, I would suggest using identifiers
that are suggestive of the function to be performed rather than their
numeric value. Something like
enum {INSERT=1, DELETE, EDIT, COMPUTE};
and then you could later amend it to
enum {INSERT=1, DELETE, EDIT, PRINT, COMPUTE};
--
Remove del for email
这篇关于在编译时宏中增加一个数字的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
