Examples to process flat files in ILE RPG (RPG IV)
As discussed on the previous page, processing a flat file in RPG depends upon how the physical file has been created. Due to this reason you will find two different examples below.
Example 1: When flat file is created using the CRTPF command, Without DDS.
Part 1. Write to the flat file using RPG IV.
** A flat file is defined as any other ordinary Physical file.
FFlatfile IF A E Disk
** Rename the record format name
F Rename(Flatfile: FLATFILE01)
D @FirstName S 10
D @LastName S 10
D @Sex S 6
D @Age S 2 0
D W@FlatFile DS Inz
DFirstName 1 10
DLastName 11 20
DSex 21 26
DAge 27 28 0
**
IFLATFILE01
** Associate the database field with data structure.
I..............Ext-field+..................Field+++++++++L1M1..PlMnZr.
I FLATFILE W@FlatFile
** Everything set now. Use the flat flat as a physical file with four
** columns namely FirstName, LastName, Sex and Age!
** Write data to this flat file as you would do with any other PF.
C *Entry PList
C Parm @FirstName
C Parm @LastName
C Parm @Sex
C Parm @Age
** Populate file fields
C Eval FirstName = @FirstName
C Eval LastName = @LastName
C Eval Sex = @Sex
C Eval Age = @Age
** Write to the flat file
C Write FLATFILE01
C Eval *InLr = *On
C Return
Called this program two times with following commands.
call wrtflatfil parm('Maria' 'Sharapova' 'Female' X'023F')
call wrtflatfil parm('Brad' 'Pitt' 'Male' X'044F')
Output in the flat file.
Line ....+....1....+....2....+...
FLATFILE
000001 Maria Sharapova Female23
000002 Brad Pitt Male 44
****** ******** End of report ********
Part 2:- Read a flat file using RPG IV
FFlatfile IF A E Disk
** Rename the record format name
F Rename(Flatfile: FLATFILE01)
D W@FlatFile DS
DFirstName 1 10
DLastName 11 20
DSex 21 26
DAge 27 28 0
**
IFLATFILE01
** Associate the database field with data structure.
I FLATFILE W@FlatFile
** Everything set now. Use the flat flat as a physical file with four
** columns namely FirstName, LastName, Sex and Age!
** Read data from this flat file as you would do with any other PF.
C Read FLATFILE01
C DoW Not %EoF(FLATFILE)
C FirstName Dsply
C LastName Dsply
C Sex Dsply
C Age Dsply
C Read FLATFILE01
C EndDo
C Eval *InLr = *On
C Return Output of sample run of the program.
DSPLY Maria DSPLY Sharapova DSPLY Female DSPLY 23 DSPLY Brad DSPLY Pitt DSPLY Male DSPLY 44
You must be happy to see your data separately, ain't you?
Example 2: When flat file has been created from a DDS.
As explained earlier, this time we do not need the I-Spec renaming. Instead we can just write an Eval statement which populates the data structure.
The source code of the example which reads such a flat file has been given below.
FFlatfile IF A E Disk
D W@FlatFile DS
DFirstName 1 10
DLastName 11 20
DSex 21 26
DAge 27 28 0
** Read the flat file
C Read FLATFILE01
C Eval W@FlatFile = FLATRCD
C FirstName DSPLY
C LastName DSPLY
C Sex DSPLY
C Age DSPLY
C Eval *InLr = *On
C Return Notice that we do not need any renaming here. In this example, the attributes of the flat file are as below.
- Name of the flat file object – FLATFILE
- Name of the record format – FLATFILE01
- Name of the DDS field – FLATRCD.
The above example illustrates only how to read such a flat file. However, you can yourself modify this source according to your need to write, delete or update any specific record of this flat file.
With this example, I end this long article (published in three days!) now. Your valuable comments and/ or feedback are most welcome.
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