"Dynamic" creation of variables through macros

Hi,
I wanted to know if something like this is possible:

#define CREATEVAR(X) X##__LINE__

but expanding the __LINE__ macro.

I'm trying to create a variable's name through a macro that could be called different times creating different names:
int CREATEVAR(a);
int CREATEVAR(a);

(of course, in this case it would only work if the macro was called in different lines).

The thing is that after the concatenation operator ## the macros don't get expanded, so, I'd like to know if there's any way around this.

Thank you.

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"Dynamic" creation of variables through macros

isha_2
Hi -

I found this code at http://msdn2.microsoft.com/en-us/library/b0084kay.aspx, in the section describing __COUNTER__

-----------------------------
```
// pre_mac_counter.cpp
#include <stdio.h>
#define FUNC2(x,y) x##y
#define FUNC1(x,y) FUNC2(x,y)
#define FUNC(x) FUNC1(x,__COUNTER__)

int FUNC(my_unique_prefix);
int FUNC(my_unique_prefix);

int main() {
  my_unique_prefix0 = 0;
  printf_s("\n%d",my_unique_prefix0);
  my_unique_prefix0++;
  printf_s("\n%d",my_unique_prefix0);
}
```
---------------------------

The three FUNC macros do what you want.

In this code, the first "int FUNC(my_unique_prefix);" global variable becomes "int my_unique_prefix0;", and the second one becomes "my_unique_prefix1" (that's the way the __COUNTER__ predefined macro works...it just keeps incrementing)

I tried it with __LINE__ instead of __COUNTER__, and it works there, too. I don't know how you plan on using a variable whose name is variable, though...

Good luck,

Brad
DragonSpeed
Thank you,
I forgot to mention that I needed it to be ansi and __COUNTER__ is VS specific.

EDIT:

I did it just replacing the __COUNTER__ with __LINE__.

#define FUNC2(x,y) x##y
#define FUNC1(x,y) FUNC2(x,y)
#define FUNC(x) FUNC1(x,__LINE__)

Can someone tell me why we need to encapsulate things this way (with various macros) so we can do this kind of concatenation
"Dynamic" creation of variables through macros

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