This example will create a stream file that contains some demonstration records. It will then show you how to look up the records, update some of the information in them, and even search through the file to find them.
Here's the code. Once again, read the code over and see if you can figure out what it does. Then, run the program and see if you're right!
* CH4FIXED: Example of fixed-length records in an IFS file
* (From Chap 4)
*
* To compile:
* CRTBNDRPG CH4FIXED SRCFILE(xxx/QRPGLESRC) DBGVIEW(*LIST)
*
H DFTACTGRP(*NO) ACTGRP(*NEW) BNDDIR('QC2LE')
D/copy IFSEBOOK/QRPGLESRC,IFSIO_H
D/copy IFSEBOOK/QRPGLESRC,ERRNO_H
D dsRecord DS
D PartNo 10S 0
D Quantity 10I 0
D UnitOfMeas 3A
D Price 7P 2
D Description 50A
D fd S 10I 0
D err S 10I 0
D MyStat S like(statds)
D recno S 10I 0
D NumRec S 10I 0
D SaveRec S 10I 0
D Pos S 10I 0
c exsr MakeFile
c eval fd = open('/ifstest/ch4_records': O_RDWR)
c if fd < 0
c callp die('open(): ' + %str(strerror(errno)))
c endif
c exsr UpdateEx
c exsr SearchEx
c callp close(fd)
c eval *inlr = *on
C****************************************************************
C* This creates a file in the IFS containing fixed-length
C* records.
C****************************************************************
CSR MakeFile begsr
C*------------------------
c eval fd = open('/ifstest/ch4_records':
c O_WRONLY+O_CREAT+O_TRUNC:
c S_IRUSR+S_IWUSR+S_IRGRP)
c if fd < 0
c callp die('open(): ' + %str(strerror(errno)))
c endif
c eval PartNo = 5001
c eval Quantity = 14
c eval UnitOfMeas = 'BOX'
c eval Price = 7.95
c eval Description = 'BLUE WIDGETS'
c callp write(fd:%addr(dsRecord):%size(dsRecord))
c eval PartNo = 5002
c eval Quantity = 6
c eval UnitOfMeas = 'BOX'
c eval Price = 3.95
c eval Description = 'RAINBOW SUSPENDERS'
c callp write(fd:%addr(dsRecord):%size(dsRecord))
c eval PartNo = 5003
c eval Quantity = 19
c eval UnitOfMeas = 'SEA'
c eval Price = 29.95
c eval Description = 'RED BICYCLE SEATS'
c callp write(fd:%addr(dsRecord):%size(dsRecord))
c eval PartNo = 5004
c eval Quantity = 8
c eval UnitOfMeas = 'ITM'
c eval Price = 93512.80
c eval Description = 'REALLY EXPENSIVE ITEMS'
c callp write(fd:%addr(dsRecord):%size(dsRecord))
c eval PartNo = 5005
c eval Quantity = 414
c eval UnitOfMeas = 'BAT'
c eval Price = 11.41
c eval Description = 'BATS IN THE BELFRY'
c callp write(fd:%addr(dsRecord):%size(dsRecord))
c eval PartNo = 5006
c eval Quantity = 125
c eval UnitOfMeas = 'BOX'
c eval Price = 1.23
c eval Description = 'KATES OLD SHOES'
c callp write(fd:%addr(dsRecord):%size(dsRecord))
c callp close(fd)
C*------------------------
CSR endsr
C****************************************************************
C* This demonstrates updating our fixed-length record file:
C****************************************************************
CSR UpdateEx begsr
C*------------------------
C* Someone bought a box of suspenders, and we want to change
C* the quantity:
C* The suspenders are in record number 2, so get them now:
c eval recno = 2
c eval pos = %size(dsRecord) * (recno-1)
c callp lseek(fd: pos: SEEK_SET)
c callp read(fd: %addr(dsRecord):%size(dsRecord))
c eval Quantity = Quantity - 1
c callp lseek(fd: pos: SEEK_SET)
c callp write(fd:%addr(dsRecord):%size(dsRecord))
C* Kate's shoes need to move faster, put them on sale!
c eval recno = 6
c eval pos = %size(dsRecord) * (recno-1)
c callp lseek(fd: pos: SEEK_SET)
c callp read(fd: %addr(dsRecord):%size(dsRecord))
c eval Price = 0.25
c callp lseek(fd: pos: SEEK_SET)
c callp write(fd:%addr(dsRecord):%size(dsRecord))
C*------------------------
CSR endsr
C****************************************************************
C* This demonstrates searching for a record in the file:
C****************************************************************
CSR SearchEx begsr
C*------------------------
C* GASP! I can't remember the record number for Bats!
C* The part number was 5005, let's search for it
c if fstat(fd: %addr(mystat)) < 0
c eval err = errno
c callp close(fd)
c callp die('fstat(): ' + %str(strerror(err)))
c endif
c eval p_statds = %addr(mystat)
c eval numrec = st_size / %size(dsRecord)
c eval SaveRec = -1
c for recno = 1 to numrec
c eval pos = %size(dsRecord) * (recno-1)
c callp lseek(fd: pos: SEEK_SET)
c callp read(fd: %addr(PartNo): %size(PartNo))
c if PartNo = 5005
c eval SaveRec = recno
c leave
c endif
c endfor
c if SaveRec = -1
c callp close(fd)
c callp die('Part no 5005 not found!')
c endif
C*------------------------
CSR endsr
/DEFINE ERRNO_LOAD_PROCEDURE
/COPY IFSEBOOK/QRPGLESRC,ERRNO_H