Re: Help with parameter passing

[Hans Boldt <boldt@xxxxxxxxxx>]

DeLong, Eric wrote:

> Hi everybody,
>
> We're trying to integrate a vendor supplied service program, written in C,
> into our RPGIV applications.  We've attempted to translate the .H include
> into RPG prototypes, and have encountered a usage problem.
>
> One of the functions is passing tax_amt and tax_rate as 
>
> double *pTransTotalTax,
> double *pTransCombRate,
>
> which we've coded as
>
> D  pTransExtdAmt                 8f         
> D  pTransTotalTx                 8f         
>
> So far so good.  Now the problem.  The use of this api states:
>
> "Total tax amount for the transaction. This parameter is used when
> processing special (tax-only debit and tax-only credit) transactions. This
> parameter is ignored if NULL is passed. Passing 0 results in zero tax being
> calculated."
>
> Entended amount is fine, since we will have a calculated value for that
> every time we call the api.  But for the call to work properly, we must send
> the other parm as NULL.  How in the he!! am I supposed to do that?  Does C
> consider a parm to be null if the address is null? 
>
> Can anyone give me some insight? 
>
> Thanks in advance....

You could define the parameters as:

D  pTransExtdAmt                  *   VALUE
D  pTransTotalTx                  *   VALUE

and either pass *NULL or %ADDR(TAXVALUE) as the parameter.

Cheers! Hans