#define macro with multiple parrams

[JohnZ]

Hi,
I'm trying to define a macro that calls a log function:

#define LOG(level, device, pcString, args ...) if (level < SERIAL_LOG_LEVEL) _log(device, pcString, ## args)

void _log (unsigned char device, const char *pcString, ...);

I want the macro to accept multiple args with "..." but the compiler didn't like it. It works fine if i simply do.

#define LOG(level, device, pcString, args ) if (level < SERIAL_LOG_LEVEL) _log(device, pcString, ## args)

and when i call

d = 0;

LOG(1, 0, "hello world %d", d);

What am i doing wrong?

Thank you for your help.

Regards,

John

[gpraghuram]

I think you miss the, after the args in the #define.

Raghu

[JohnZ]

I think you miss the, after the args in the #define.

Raghu

Ok, that works with 1 or more arguments, but if i do

LOG(1, 0, "hello world");

compiler says too few argument in macro.

I'm using IAR by the way.

Thank you.

[gpraghuram]

Ok, that works with 1 or more arguments, but if i do

LOG(1, 0, "hello world");

compiler says too few argument in macro.

I'm using IAR by the way.

Thank you.

Since you have specified 4 args followed by elipsis it is expecting 4 arguments atleast.
Then you shuld change the Macro....


Raghu

[JohnZ]

Since you have specified 4 args followed by elipsis it is expecting 4 arguments atleast.
Then you shuld change the Macro....


Raghu

Shouldn't the "..." allow 0 or more arguments? so that the below should accept 3 arguments or more.

#define LOG(level, device, pcString, ...) \
if (level < SERIAL_LOG_LEVEL) _log(device, pcString, ## __VA_ARGS__)

Shouldn't it?

Thank you.

[JosAH]

Shouldn't the "..." allow 0 or more arguments? so that the below should accept 3 arguments or more.

#define LOG(level, device, pcString, ...) \
if (level < SERIAL_LOG_LEVEL) _log(device, pcString, ## __VA_ARGS__)

Shouldn't it?

Thank you.

This is what the C99 Standard says about it:

[#12] If there is a ... in the identifier-list in the macro
definition, then the trailing arguments, including any
separating comma preprocessing tokens, are merged to form a
single item: the variable arguments. The number of arguments
so combined is such that, following merger, the number of
arguments is one more than the number of parameters in the
macro definition (excluding the ...).

kind regards,

Jos

[JohnZ]

This is what the C99 Standard says about it:



kind regards,

Jos

Thank you very much, I understand what I'm doing wrong now.