varying number of arguments CVI 7.1

[olhass]

Hello,

anyone knows how it's possible to declare functions with a varying number of arguments in CVI 7.1? (later CVI versions can use C99 extension macro)

example: Func(int i, ... );

Thanks

[RobertoBozzolo]

This is definitely possible by means of va_list and va_start macros: I have been using it since at least CVI5.

See this example program

[olhass]

And what about macros?

example: #define MACRO(param1, ...)

[RobertoBozzolo]

What do you mean with "macros"? va_start and va_arg already are macros, defined in stdarg.h

[olhass]

I meant a self defined macro with variable arguments - here '...' doesn't work - you will get a compiler error because this is a C99 extension - you have to use __VA_ARGS__

example: #define MACRO(param1, __VA_ARGS__)

[LuisG]

Variable-length macros are supported only in CVI 9.0 and later.

Luis

[olhass]

That's not right, you can use "__VA_ARGS__" instead of "..." for defining variable macro length...

[LuisG]

I'm not exactly sure what you mean. This is how you're supposed to use variable argument macros:

   #define debug_printf(format, ...) fprintf (stderr, format, __VA_ARGS__);
   debug_printf ("%s %s %s", "a", "b", "c");

You can do this in CVI 9.0 and later. You cannot do it in CVI 7.1.

You say that you can replace "..." with "__VA_ARGS__"? How, exactly? Like this?

   #define debug_printf(format, __VA_ARGS__) fprintf (stderr, format, __VA_ARGS__);
   debug_printf ("%s %s %s", "a", "b", "c");

That doesn't work in any version of CVI, so far as I know.