How to get rid of unused parameter warnings?

void DoSomething(int a, int b)
{

(void)b;

SomeOtherFunction(a);
}

Also gives warning expression with possibly no effect.

void DoSomething(int a,int) {
    SomeOtherFunction(a);
}

Thanks for that but it gives the same "non standard expression - unnamed parameter" warning as described above.

Oops - didn't see you had tried that. Stupid Keil compiler.

This is an old chestnut - it comes up again and again!

Some compilers are thoughtful enough to provide some kind of #pragma or similar to handle this.

Otherwise, it's a matter of finding some bening bit of code that doesn't then give some other warning - as you've found...

Have you tried

void DoSomething(int a, int b)
{

   b=b;
}

"benign"

I have found that works with several compilers:

if (b);

If you want the code to be protable between compilers, you might want to wrap the 'silencing' code by a macro:

#define UNUSED_ARG(x) do { if (x) ; } while (0) /* or whatever */

Besides, it will probably make the code more readable.

I think that the conclusion from this thread is that the solution is not portable - because what "works" on one compiler may not on another.

To make it "portable", you'd need comditional-compilation to select the appropriate construct for the particular compiler...

But the technique of wrapping an "executable" macro in do{...}while(0) is a common one:

c-faq.com/.../multistmt.html

per c166 docs:

#pragma warning disable = 47

http://www.keil.com/support/man/docs/c166/c166_warning.htm

Doesn't seem to be an option to "restore previous setting", though?

Wow, I didn't expect so many helpful replies. Thanks for all the good advice. I also tried the if(b); option but it gives an expression has no effect warning. So, the conclusion seems to be that disabling the warning is the only option.

If it did work I would definitely think an unused() macro would be the way to go.

I don't really like to remove the warning as it has saved me before from doing something done and is good for pointing out potential design issues in your code. I guess I can live with it for now fortunately they are in modules that are rarely recompiled.

Thanks for all the advice...

I don't really like to remove the warning as it has saved me before from doing something

I have to agree here. There should be a possibility to mark a singular parameter. I definitely want a warning like this in general. But I want to turn it off if I keep a parameter to conform with a certain interface.

Lints /* ARGSUSEDn */ comes to mind.