IBM Version 4 manual Correct Byte Alignment ensures that data used With an

Defining Byte Alignment
Correct	byte	alignment ensures that data used	with an	API	is	correct.
ment is	also essential when APIs are used to		retrieve	and then print
data. When byte alignment is off, it causes			the API	to	read	the da
other	than at	the beginning of a record.

Defining

Byte

Alignment—Example

of

Incorrect

Coding

This

program

illustrates

byte

alignment

while

defining

a

structure. This

i

.14/ on page 9-23. Four-byte alignment is required when using this

progra

Variable-length records must begin on a 4-byte boundary.14/, . theAs shown

at

variable-length

record

CCSID_rec

is

not

beginning

on a

4-byte

boundary.

the

API

accesses

the

CCSID_rec record, 4-byte alignment is

forced

by

first 3 bytes of the CCSID_rec

between

the

replace

field

and

the

CCSID_rec record.15/. on

page

9-24

shows that the variable-length

record

not 4-byte aligned

(the value

is

13,

which is

not

divisible

by

4). T

is

shown

.at17/

on page 9-26.

Note:

Not

all

APIs require a 4-byte boundary. ILE APIs, such as

QusAddExitProgram,

do.

/\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

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/\

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/\Program Name: PGM1

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/\

\/

/\Program Language: ILE C

\/

/\

\/

/\Description:

This program illustrates improper byte

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/\

alignment when using variable length

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/\

records.

\/

/\

\/

/\

\/

/\Header Files Included:

<stdio.h>

\/

/\

<signal.h>

\/

/\

<string.h>

\/

/\

<stdlib.h>

\/

/\

<qusrgfa1.h>

\/

/\

<qusec.h>

\/

/\

<qliept.h>

\/

/\

\/

/\

APIs Used:

QusAddExitProgram

- Add an exit program

\/

/\

\/

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/\

Includes

\/

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#include <stdio.h>

#include <signal.h>

#include <string.h>

#include <stdlib.h>

#include <qusrgfa1.h>

#include <qusec.h>

#include <qliept.h>

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/\

Structures

\/

9-22

System API

Programming

V4R1