IBM AS/400 manual Calling within an Expression, Using a Prototyped Call

Using a Prototyped Call

To call a prototyped program or procedure follow these general steps:

1.Include the prototype of the program or procedure to be called specifications.

2.Enter the prototype name of the program or procedure in the exte

	field, followed by the parameters if any, within parentheses. Separ
	parameters with			a	colon	(:).	Factor	1	must	be	blank.
The	following		example shows			a call to a procedure Switch, which changes
of	the	indicator		that	is	passed to it,			in	this	case *IN10..
	C			CALLP	Switch(*in10)
A maximum		of	255 parameters			are	allowed	on	a	program call, and a maximum
399	for	a	procedure		call.

You can use CALLP from anywhere within the module. If the keyword EXTPG specified on the prototype, the call will be a dynamic external call; be a bound procedure call.

Note	that	if CALLP is used to call a	procedure	which returns	a	value,
not be available to the caller. If			the value	is required,	call	the
within	an	expression.

Calling within an Expression

If a	prototyped	procedure is defined to return a	value	then	you mu
dure within an expression if you want to make use of			the	return		valu
procedure name in		a manner that is consistent with the	data type			of
return	value. For	example, if a procedure is defined	to	return	a	num

call to the procedure within an expression must be where a numeric wo expected.

Figure 61 shows the prototype for a procedure CVTCHR that takes a nume parameter and returns a character string. Figure 62 shows how the proc might be used in an expression.

*Prototype for CVTCHR

*- returns a character representation of the numeric param￿eter

	* Examples: CVTCHR(5) returns '5			'
	*	CVTCHR(15-124) returns '-109			'
D CVTCHR		PR	31A
D	NUM		30P 0	VALUE
Figure	61.	Prototype for CVTCHR
C		EVAL	STRING =	'Address: ' +
C				%TRIM(CVTCHR(StreetNum))
C				+ ' ' + StreetName
	* If STREETNUM = 427 and STREETNAME =			'Mockingbird Lane', afte￿r the
	* EVAL operation STRING = 'ADDRESS: 427 Mockingbird Lane'
Figure	62.	Calling a Prototyped Procedure within an Expression

134 ILE RPG for AS/400 Programmer's Guide