Defining Data Structures

When a data structure is defined for use with an API, the struct receive what the API returns.

The use of IBM-supplied data structures eliminates having to create structures. For information on IBM-supplied data structures that are c library QSYSINC, see “APIs and the QSYSINC Library” on page 2-28.

Defining a Data Structure—Example

of

Incorrect

Coding

 

 

 

 

 

 

 

 

 

When the

program

that defines

a

data

structure

is run, it

does

th

Ÿ

Creates

a

user

space

 

 

 

 

 

 

 

 

 

 

 

Ÿ

Retrieves

a

list

of

active

jobs

 

 

 

 

 

 

 

Ÿ

Displays

the

first part of a job name

 

 

 

 

 

 

Ÿ

Deletes

the

user

space

that

held

the

data

 

 

 

 

In

this

example,

the data structure to be used with the QUSLJOB

defined incorrectly. The incorrectly defined

variables

are JNAME and

The

JNAME

length is

defined

as

1

through 12

and

the

USRNAM

length

as

through 20.

This

is

 

shown.5/

onat

page

9-5. The data displayed (JNAME vari-

able) will be incorrect. The correct coding.6/

onispageshown9-7.at

 

 

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

 

 

 

\

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

\Program Name: PGM1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

\

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

\Program Language:

RPG

 

 

 

 

 

 

 

 

 

 

 

 

 

\

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

\Description: This sample program illustrates the incorr￿ect

 

 

 

 

\

 

 

way of defining data structures.

 

 

 

 

 

 

 

\

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

\Header Files Included: QUSEC - Error Code Parameter

 

 

 

 

 

 

\

 

 

 

 

 

QUSGEN - User Space Format for Generic Header

 

 

\

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

\APIs Used:

QUSCRTUS

- Create User Space

 

 

 

 

 

 

 

\

 

 

QUSLJOB

- List Job

 

 

 

 

 

 

 

 

 

 

\QUSRTVUS - Retrieve User Space

\QUSDLTUS - Delete User Space

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

\THIS PROGRAM WILL CREATE THE NECESSARY SPACE AND THEN CA￿LL

\THE QUSLJOB API TO GET A LIST OF ALL ACTIVE JOBS ON THE SYS￿TEM.

\THE FIRST JOB NAME/USER WILL BE DISPLAYED TO THE USER.

\

\BRING IN THE USER SPACE GENERIC HEADER I/COPY QSYSINC/QRPGSRC,QUSGEN

\BRING IN THE ERROR STRUCTURE FROM QSYSINC I/COPY QSYSINC/QRPGSRC,QUSEC

\\ JOB NAME STRUCTURE FOR CALLING QUSLJOB

IJOBNAM

DS

 

 

 

 

I I

'\ALL

'

1

1ð JOB

I

I

'\ALL

'

11

2ð

USER

I

I

'\ALL

'

21

26

JOBNUM

\\JOBLð1ðð FORMAT RETURNED FROM QUSLJOB API

\\INCORRECTLY CODE THE JNAME/USRNAM LENGTHS

IRECVR

DS

 

 

I

1

12 JNAME

.5/

 

Chapter

9. Common

API Programming Errors 9-5

Page 210 Page 212
Page 211
Image 211
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