C++ macro with variable number of arguments

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C/C++: How to make a variadic macro (variable number of arguments)

I need macro that will expand in a array that contains it's arguments. For example:

#define foo(X0) char* array[1] = {X0}
#define foo(X0, X1) char* array[2] = {X0, X1}

and so on. My problem is that I need to use foo with variable number of arguments, so I want to be able to use foo("foo0") but also to use foo("foo0", "foo1", "foo2"..."fooN"). I know it's possible to have:

#define foo(...)
#define foo_1(X0) ..
#define foo_2(X0, X1) ..
#define foo_3(X0, X1, X2) ..
#define foo_N(X0, X1, ... XN) ..

And use ____VA_ARGS____, but I don't know how may I expand foo in foo_k macro depending on it's parameter count? Is this possible?

I didn't know that __VA_ARGS__ expand also the commas:). Stupid me:) — Mircea Ispas, Mar 12 '11 at 15:16
Have you looked into: http://www.boost.org/doc/libs/1_46_0/libs/preprocessor/doc/index.html — julx, Mar 12 '11 at 14:58
I don't want boost. It's to heavy to carry in a small project! — Mircea Ispas, Mar 12 '11 at 15:01
so is libstd, however you don't carry it with you, you require it as a dependencies. — Joel Falcou, May 07 '12 at 11:15

score 20 · Accepted Answer · answered Mar 12 '11 at 15:14

20

How about:

#define FOO( ... ) char* x[] = { __VA_ARGS__ };

answered Mar 12 '11 at 15:14

JoeSlav

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Paul R · Answer 2 · 2013-08-25T06:03:27.340

3

This should work:

#define foo(args...) char* array[] = {args}

Note that this uses a GNU extension and so will only work with gcc and gcc-compatible compilers. @JoeSlav's answer using __VA_ARGS__ is more portable.

edited Aug 25 '13 at 06:03

answered Mar 12 '11 at 15:11

Paul R

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#define foo(...) char* array[] = {__VA_ARGS__} – Mircea Ispas Mar 12 '11 at 15:15
I think this should be marked as the right answer. – neevek Jun 03 '12 at 02:12

score 0 · Answer 3 · edited May 23 '17 at 12:18

0

I recommend gcc.gnu.org docs on the subject.

Or you could jump straight away to this answer:

How to make a variadic macro (variable number of arguments)

edited May 23 '17 at 12:18

Community

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answered Mar 12 '11 at 15:16

karlphillip

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C++ macro with variable number of arguments

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