IBM AS/400 manual Passing by Value, Passing Prototyped Parameters

Passing Prototyped Parameters

Passing by Value

With a prototyped procedure, you can pass a parameter by value inst reference. When a parameter is passed by value, the compiler passes value to the called procedure.

Note: OS/400 program calls require that parameters be passed by refere Consequently, you cannot pass a parameter by value to a program.

Passing by value allows you to:

¹ Pass literals and expressions as parameters.

¹Pass parameters that do not match exactly the type and length that expected.

¹ Pass a variable that, from the caller's perspective, will not be mod

When a parameter is passed by value, the called program or procedure change the value of the parameter, but the caller will never see the

One

primary use for

passing by

value

is

that

you

can

allow

less

strin

of the attributes of the passed parameter.

For

example,

if

the

def

numeric field

of type packed-decimal

and

length

5

with

2

decimal

posit

must

pass a

numeric

value, but

it can

be:

¹A packed, zoned or binary constant or variable, with any number of

number of decimal positions

¹	A	built-in function returning a numeric value
¹	A	procedure returning a numeric value
¹	A	complex numeric expression such as
		2 * (Min(Length(First) + Length(Last) + 1): %size(Name))

If the prototype requires an array of 4 elements, the passed param

¹	An	array	with	fewer		than	4	elements. In this case, the remaining
	the received			parameter will				contain the default value for	the	type
¹	An	array	with	4	elements.		In	this case, each element of	the	rece
	will	correspond		to	an	element		of the passed parameter.

¹An array with more than 4 elements. In this case, some of the ele

passed array will not be passed to the received parameter.

¹ A non-array. In this			case, each element of the received parameter
the	passed	parameter	value.
To pass a parameter by			value, specify	the keyword VALUE on the para
nition	in the	prototype,	as shown in the	figures below.

136 ILE RPG for AS/400 Programmer's Guide