how could I write this cpp macro

[Bilgehan.Balban]

Hi,

I'm trying to convert this:

printf("format str %s, %s", "str arg 1", "str arg 2 etc.");

to this:

printf("%s: " "format str %s, %s", __FUNCTION__, "str arg 1", "str arg2
etc.");

All sol'ns I came up had various problems in various printf formats.
The closest I had was something like:

#if DEBUG > 0
#define pdebug(fmt ...) printf("%s: " fmt, \
__FUNCTION__, __VA_ARGS__); \
#endif

But this wont work if there's a printf with no va_args, such as:

printf("fmt string and nothing else\n");

because the comma after __FUNCTION__ will be a syntax error.

Any ideas?

Thanks,
Bahadir

 

[Ben Pfaff]

I'm trying to convert this:

printf("format str %s, %s", "str arg 1", "str arg 2 etc.");

to this:

printf("%s: " "format str %s, %s", __FUNCTION__, "str arg 1", "str arg2
etc.");

It's ghastly, but
#define pdebug printf("%s:", __FUNCTION__), printf
might do what you want.

There are probably C99-specific solutions, and definitely
GCC-specific solutions, as well.

 

[L7]

Hi,

I'm trying to convert this:

printf("format str %s, %s", "str arg 1", "str arg 2 etc.");

to this:

printf("%s: " "format str %s, %s", __FUNCTION__, "str arg 1", "str arg2
etc.");

All sol'ns I came up had various problems in various printf formats.
The closest I had was something like:

#if DEBUG > 0
#define pdebug(fmt ...) printf("%s: " fmt, \
__FUNCTION__, __VA_ARGS__); \
#endif

But this wont work if there's a printf with no va_args, such as:

printf("fmt string and nothing else\n");

because the comma after __FUNCTION__ will be a syntax error.

Any ideas?

#define pdebug(args...) do { \
printf ("%s:", __FUNCTION__); \
printf (args); \
} while (0);

Should do what you want.

 

[David Resnick]

It's ghastly, but
#define pdebug printf("%s:", __FUNCTION__), printf
might do what you want.

There are probably C99-specific solutions, and definitely
GCC-specific solutions, as well.

I think Ben's solution or a variant of it may be what you want. Your
method of concatenating string literals precludes people from using a
variable as the format string, not ideal if this is to be widely used.
e.g.

const char *format = "%s %d %s";
pdebug(format, foo, bar, bas);

would break.

-David

 

[Eric Sosman]

L7 wrote On 08/31/06 13:58,:

#define pdebug(args...) do { \
printf ("%s:", __FUNCTION__); \
printf (args); \
} while (0);

Should do what you want.

Lose the final semicolon.

 

[Ben Pfaff]

#define pdebug(args...) do { \
printf ("%s:", __FUNCTION__); \
printf (args); \
} while (0);

That's GCC-specific.