IBM Version 4 manual Parameter Passing, Value of the data object is placed directl, Parameter List

ters (A through Z,	0 through 9,	$,	#,	@,	),	or	_). The system uses
as is, and it does	not change	or	check		the		object	name	before	lo
This improves the performance of		the		API. An		incorrect		name	usually	re
Object not found error.

Parameter Passing

With the exception of the		UNIX-type APIs, the standard protocol		is
pointer that points to	the	information that	is being passed. (This	is
as pass-by-reference.)	This	is the convention	automatically used by	CL,

COBOL compilers. If you are using a language that supports pointers, ensure that these conventions are followed. Refer to the appropriate

umentation

for

instructions.

Refer

to “Selecting

the High-Level

Language

on

page 2-3

for

a table

that discusses

the

high-level

languages.

In

an

OPM

or

ILE

parametercall,

a

is

an

expression

that

represents

a

value

the

calling

application

passes

to

the API specified in the call. HLL

the

following

methods

for

passing

parameters:

by

value,

directly

The value of the data object is placed directl

parameter

list.

by

value,

indirectly

The

value

of

the data object is copied to a

location. The

address

of

the

copy

(a pointer)

is

into the parameter list. By value, indirectly is

explicitly

by

the application programmer. It is d

the

operating

system

at

run

time.

by

reference

A

pointer

to

the data object is placed

into

th

list. Changes made by the

called API to

the par

are reflected in the calling application.

Figure 2-4 illustrates these parameter passing styles. Not all

HLL

langua

support

all

styles.

By

value,

directly

a copy of argument

By

value,

indirectly

pointer

a copy of argument

By reference

pointer

the actual argument

RV2W1027-1

Figure 2-4. Methods for Passing Parameters

HLL semantics usually determine when data is passed by value and whe passed by reference. For example, ILE C passes and accepts paramet value, directly, while for OPM and ILE COBOL and OPM and ILE RPG param are usually passed by reference. You must ensure that the calling p

Chapter 2. Getting Started with2-7APIs