Re: Procedure PR/PI question

On 5/1/2013 6:14 AM, whatt sson wrote:

...
if i need to pass lots of data (in principle always if i want to pass more
than just a basic type) i pass a pointer. ... I don't see a real
downside in this approach ...

RPG doesn't have typed pointers.

Take this C function
myFn (int *p);

The exact RPG equivalent is

D myFn PR
D p 10i 0

Both the C and RPG prototypes say that the parameter is an integer passed by reference. The C version can also be stated as "pointer to integer passed by value". But that's not possible to code in RPG. This RPG prototype

D myFn PR
D p * value

is not equivalent to the C prototype, because that RPG prototype simply says "pointer passed by value". The "integer" part of the C prototype is lost.

If you pass the address of a float to the C function, the C ocmpiler will complain. If you pass the address of a float to the second RPG function, the RPG compiler won't care, because you haven't told it to expect a pointer to an integer.

If you decide to manage passing the correct data types yourself, you're back in the bad old days of CALL + PARM, where the compiler oculd not do any type checking.