预处理器q：不可能的宏？ [英] preprocessor q: impossible macro?
问题描述
大家好，
我已经得到了这行代码（不能改变这个;向导生成，但
值有朝一日可能会改变）：
#define IDB_BUTTON 225
代码中的某个地方我发现/需要这个：
..... somefunction（&＃ 225）....
函数调用中的这个字符串与define中的字符串相同，但
常量未被使用。因为为了将来的更改和可读性，我想要用这样的预处理器宏来创建这个字符串：
..... somefunction（MYMACRO（IDB_BUTTON））.. ..
我没有得到这样的宏工作。我试过了：
#define MYMACRO（num）"＃" #num
但这只会产生
..... somefunction（＃，IDB_BUTTON）....
我也尝试过使用令牌粘贴操作员（##）等。
这可能吗？
Eric
Hello all,
I''ve got this line of given code (cannot change this; wizard-generated, but
value may change someday):
#define IDB_BUTTON 225
Somewhere in the code I found / need this:
.....somefunction("#225")....
This string in the function call is the same number like in the define, but
the constant wasn''t used. Because for future changes and for readability I
wanted to create this string with a preprocessor macro like this:
.....somefunction(MYMACRO(IDB_BUTTON))....
I didn''t get such a macro to work. I tried:
#define MYMACRO(num) "#" #num
but this only yields to
.....somefunction("#" "IDB_BUTTON")....
I also tried with the token-pasting operator (##) etc.
Is this possible at all?
Eric
推荐答案
Eric写道：
我有这行代码（不能改变这个;向导生成，但是
价值可能会在某一天发生变化）：
#define IDB_BUTTON 225
代码中的某处我发现/需要这个：
.... somefunction（＃225）.. ..
函数调用中的这个字符串与define中的字符串相同，但
该常量未被使用。因为为了将来的更改和可读性，我想用这样的预处理器宏创建这个字符串：
.... somefunction（MYMACRO（IDB_BUTTON））....
我没有得到这样的宏观工作。我试过了：
#define MYMACRO（num）"＃" #num
但这只会产生
.... somefunction（＃" IDB_BUTTON"）....
我也尝试过使用令牌粘贴操作符（＃ ＃）等
这有可能吗？
I''ve got this line of given code (cannot change this; wizard-generated, but
value may change someday):
#define IDB_BUTTON 225
Somewhere in the code I found / need this:
....somefunction("#225")....
This string in the function call is the same number like in the define, but
the constant wasn''t used. Because for future changes and for readability I
wanted to create this string with a preprocessor macro like this:
....somefunction(MYMACRO(IDB_BUTTON))....
I didn''t get such a macro to work. I tried:
#define MYMACRO(num) "#" #num
but this only yields to
....somefunction("#" "IDB_BUTTON")....
I also tried with the token-pasting operator (##) etc.
Is this possible at all?
是的，你需要一个间接的字符串化宏观。
#define STR（x）#x
#define MYMACRO（num）"＃" ## STR（num）
#define IDB_BUTTON 225
#include< stdio.h>
int main（无效）{
printf（" Got％s \ nn"，MYMACRO（IDB_BUTTON））;
}
V
Yes, you need an indirect "stringizing" macro for that.
#define STR(x) #x
#define MYMACRO(num) "#" ## STR(num)
#define IDB_BUTTON 225
#include <stdio.h>
int main(void) {
printf("Got %s\n", MYMACRO(IDB_BUTTON));
}
V
Victor Bazarov写道：
Victor Bazarov wrote:
Eric写道：
我已经得到这行给定的代码（不能改变这个;向导生成，但
值可能有一天会改变）：
#define IDB_BUTTON 225
代码中的某处我发现/需要这个：
.... somefunction（＃225）....
函数调用中的这个字符串与定义中的数字相同，但是
常数没用过。因为为了将来的更改和可读性，我想用这样的预处理器宏创建这个字符串：
.... somefunction（MYMACRO（IDB_BUTTON））....
我没有得到这样的宏观工作。我试过了：
#define MYMACRO（num）"＃" #num
但这只会产生
.... somefunction（＃" IDB_BUTTON"）....
我也尝试过使用令牌粘贴操作符（＃ ＃）等
这有可能吗？
I''ve got this line of given code (cannot change this; wizard-generated, but
value may change someday):
#define IDB_BUTTON 225
Somewhere in the code I found / need this:
....somefunction("#225")....
This string in the function call is the same number like in the define, but
the constant wasn''t used. Because for future changes and for readability I
wanted to create this string with a preprocessor macro like this:
....somefunction(MYMACRO(IDB_BUTTON))....
I didn''t get such a macro to work. I tried:
#define MYMACRO(num) "#" #num
but this only yields to
....somefunction("#" "IDB_BUTTON")....
I also tried with the token-pasting operator (##) etc.
Is this possible at all?
是的，你需要一个间接的字符串化宏观。
#define STR（x）#x
#define MYMACRO（num）"＃" ## STR（num）
#define IDB_BUTTON 225
#include< stdio.h>
int main（void）{
printf（" Got％s \ n"，MYMACRO（IDB_BUTTON））;
}
V
Yes, you need an indirect "stringizing" macro for that.
#define STR(x) #x
#define MYMACRO(num) "#" ## STR(num)
#define IDB_BUTTON 225
#include <stdio.h>
int main(void) {
printf("Got %s\n", MYMACRO(IDB_BUTTON));
}
V
以上解决方案无法编译。由于粘贴了相邻的字符串文字，因此不需要粘贴代码
。
#define STR（x）#x
#define MYMACRO（num）＃ STR（num）
#define IDB_BUTTON 225
#include< stdio.h>
int main（void）{
printf（" Got％s \ nn"，MYMACRO（IDB_BUTTON））;
}
-Charlie
The above solution does not compile. Token pasting is not necessary
since adjacent string literals are pasted.
#define STR(x) #x
#define MYMACRO(num) "#" STR(num)
#define IDB_BUTTON 225
#include <stdio.h>
int main(void) {
printf("Got %s\n", MYMACRO(IDB_BUTTON));
}
-Charlie
Charles Mills写道：
Charles Mills wrote:
Victor Bazarov写道：
[...]
Victor Bazarov wrote:
[..]
#define STR（x）#x
#define MYMACRO（num）"＃" ## STR（num）
#define IDB_BUTTON 225
#include< stdio.h>
int main（void）{
printf（" Got％s \ n"，MYMACRO（IDB_BUTTON））;
}
V
#define STR(x) #x
#define MYMACRO(num) "#" ## STR(num)
#define IDB_BUTTON 225
#include <stdio.h>
int main(void) {
printf("Got %s\n", MYMACRO(IDB_BUTTON));
}
V
以上解决方案不编译。 [..]
The above solution does not compile. [..]
关于什么编译器？什么是错误信息？
V
On what compiler? What is the error message?
V
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