IBM AS/400 manual Passing *OMIT, Leaving Out Parameters, Passing Prototyped Parameters

Passing Prototyped Parameters

Passing *OMIT

You can pass *OMIT for a prototyped parameter if the called procedu that *OMIT might be passed. In other words, you can pass *OMIT if t OPTIONS(*OMIT) is specified on the corresponding parameter definition in totype. When *OMIT is specified, the compiler will generate the neces

indicate

to

the

called

procedure that the parameter has been omitte

Note:

*OMIT

can

only

be

specified

for

parameters

passed

by

reference

To

determine

if

*OMIT

has been

passed

to

an

ILE

RPG procedure,

use

%ADDR built-in function to

check the address of the parameter in quest

address is *NULL, then *OMIT has

been

passed.

You can also use the

(Check for Omitted Argument) bindable API. (See

Figure 65

on

page 138

fo

brief

example.)

The following is a simple

example of how *OMIT can be used. In this

procedure

calls

the

ILE

bindable

API

CEEDOD

in

order

to

decompose

an

tional descriptor. The CEEDOD API

expects

to

receive

seven

parameters;

six

have

been

defined

in the calling procedure. The last

parameter

o

(and

of

most

bindable

APIs)

is

the

feedback

code

which

can

be

used

how the API ended. However,

the

calling

procedure

has

been

designed

any

error

messages

via

an exception rather than this feedback code.

quently, on the

call

to

CEEDOD, the procedure must indicate

that the

p

the

feedback

code

has

been omitted.

See “Sample Service Program” on page 94 for an example of using *OMIT.

Leaving Out Parameters

The other way to omit a parameter is to simply leave it out on the be expected by the called procedure, which means that it must be prototype. To indicate that a prototyped parameter does not have to a call, specify the keyword OPTIONS(*NOPASS) on the corresponding parameter definition. Note that all parameters following the first *NOPASS one must a

specified with OPTIONS(*NOPASS).
You	can		specify	both *NOPASS and *OMIT		for the same	parameter, in eithe
that		is,	OPTIONS(*NOPASS:*OMIT) or		OPTIONS(*OMIT:*NOPASS).
As	an	example of		OPTIONS(*NOPASS),	consider	the system	API QCMDEXC

(Execute Command) which has an optional third parameter. To allow for th parameter, the prototype for QCMDEXC could be written as shown in Figure

*-------------------------------------------------------------

*This prototype for QCMDEXC defines three parameters:

*1- a character field that may be shorter in length

*than expected

*2- any numeric field

*3- an optional character field

	*-------------------------------------------------------------
D qcmdexc		PR		EXTPGM('QCMDEXC')
D	cmd		3000A	OPTIONS(*VARSIZE) CONST
D	cmdlen		15P	5 CONST
D			3A	CONST OPTIONS(*NOPASS)
Figure	67. Prototype for System API QCMDEXC with Optional Parameter

140 ILE RPG for AS/400 Programmer's Guide