Function to do nothing

[Michael]

Hi,
all is going fine, but I'm compiling with max warnings, and I get a lot of
warnings to tell me that some parameter passed is not being used. Is there a
way of telling the compiler that its ok? eg pointers i can do:
if( pIn) ;
then i don't get the complaint (something else instead ;-) )but I could do
with something like:

void func(int i1,int i2, int i3)
{
#pragma NOTUSED (i1,i2)

printf("%d",i3)
}

Sorry if its compiler specific.

Mike

 

[Dave Vandervies]

Hi,
all is going fine, but I'm compiling with max warnings, and I get a lot of
warnings to tell me that some parameter passed is not being used. Is there a
way of telling the compiler that its ok? eg pointers i can do:
if( pIn) ;
then i don't get the complaint (something else instead ;-) )but I could do
with something like:

void func(int i1,int i2, int i3)
{
#pragma NOTUSED (i1,i2)

printf("%d",i3)
}

Isn't this what unnamed parameters are for?

void func(int,int,int i3)
{
printf("%d",i3);
}


dave

 

[Andrew Koenig]

all is going fine, but I'm compiling with max warnings, and I get a lot
of
warnings to tell me that some parameter passed is not being used. Is there
a
way of telling the compiler that its ok? eg pointers i can do:
if( pIn) ;
then i don't get the complaint (something else instead ;-) )but I could do
with something like:

void func(int i1,int i2, int i3)
{
#pragma NOTUSED (i1,i2)

printf("%d",i3)
}

It depends on your compiler, of course, but as a general notion it would
seem that if you aren't using a parameter, you shouldn't be giving it a
name:

void func(int, int, int i3)
{
// etc.
}

 

[Maxim]

Michael wrote :

Hi,
all is going fine, but I'm compiling with max warnings, and I get a lot of
warnings to tell me that some parameter passed is not being used. Is there a
way of telling the compiler that its ok? eg pointers i can do:
if( pIn) ;
then i don't get the complaint (something else instead ;-) )but I could do
with something like:

void func(int i1,int i2, int i3)
{
#pragma NOTUSED (i1,i2)

printf("%d",i3)
}

#define NOTUSED(_V) ((void) (_V))

void func(int i1,int i2, int i3)
{
NOTUSED(i1);
NOTUSED(i2);
printf("%d",i3)
}


(follow up to comp.lang.c)

 

[Dave Vandervies]

#define NOTUSED(_V) ((void) (_V))

void func(int i1,int i2, int i3)
{
NOTUSED(i1);
NOTUSED(i2);
printf("%d",i3)
}


(follow up to comp.lang.c)

Wouldn't it make more sense to give a C++ answer and leave the thread
in clc++?

If the OP wanted a C answer, he'd've posted in comp.lang.c in the first
place, no?

And even assuming that he really wanted a C answer, your solution isn't
valid, since it uses an identifier reserved for the implementation
(see n869 7.1.3).


dave

 

[DaKoadMunky]

It depends on your compiler, of course, but as a general notion it would

seem that if you aren't using a parameter, you shouldn't be giving it a
name:

If a parameter is unnamed, and presumably therefore unusable, can the compiler
eliminate the passing of the argument to the function?

 

[David Lindauer]

If a parameter is unnamed, and presumably therefore unusable, can the compiler
eliminate the passing of the argument to the function?

probably not since the prototype can have unnamed parameters in either case...

David

 

[Michael]

Thanks guys, that was exactly what i was after.
Mike

 

[Howard]

Hi,
all is going fine, but I'm compiling with max warnings, and I get a lot
of
warnings to tell me that some parameter passed is not being used. Is there
a
way of telling the compiler that its ok? eg pointers i can do:
if( pIn) ;
then i don't get the complaint (something else instead ;-) )but I could do
with something like:

void func(int i1,int i2, int i3)
{
#pragma NOTUSED (i1,i2)

printf("%d",i3)
}

Sorry if its compiler specific.

Mike

Just an FYI: besides using unnamed parameters, you can also do this:

void func( int i1, int i2, int i3 )
{
i1;
i2;
printf("%d",i3);
}


-Howard

 

[Old Wolf]

If the OP wanted a C answer, he'd've posted in comp.lang.c in the first
place, no?

This answer works in both C and C++ (in C you cannot have unnamed
parameters).

(For some definitions of "works", one compiler I use will still
issue the warning for this form of NOTUSED).

And even assuming that he really wanted a C answer, your solution isn't
valid, since it uses an identifier reserved for the implementation
(see n869 7.1.3).

I don't think preprocessor tokens are identifiers. In the
preprocessed output, _V will not appear. If there is already
a _V defined, then it will be superseded by the new _V for the
scope of the macro definition.

For example I could go:
#include <stdio.h>
#define BAR(NULL)
BAR(a)
just fine.