Locate field value field name
You can't do this in general in RPG (or any compiled language), but if the field is in an externally-described file, you can define an externally-described data structure for the file to get the fields in the same layout in the program as they are in the file. Then you can call the QUSLFLD API to find where that field is in the data structure.
You can also use this technique to do generic processing on files. For example, if you want to check several files to ensure that all zoned fields have valid data, you could use the program below. It uses a program described file, and calls QUSLFLD to find out the location and length of all the zoned fields in the file. Then it reads the file and checks the zoned fields in every record.
If you wanted to find a particular field or set of fields by name, rather than looking for type = 'S' as this program does, you'd look for the name you were interested in (subfield fieldName).
* Parameters:
*
* 1. File name
* 2. Record name
* 3. Library name (optional, defaults to *LIBL)
*
H OPTION(*SRCSTMT : *NODEBUGIO)
Ffile if f32766 disk usropn infds(infds)
Fqsysprt o f 80 printer
D record DS 32766
D infds DS
D rrn 397 400i 0
* ==> create user space QTEMP/LIST (call the QUSCRTUS API to do this)
D userSpace C 'LIST QTEMP '
D pUserSpace S *
D genericHeader DS based(pUserSpace)
D headerOffset 117 120i 0
D headerSize 121 124i 0
D listOffset 125 128i 0
D listSize 129 132i 0
D numEntries 133 136i 0
D entrySize 137 140i 0
D filename DS
D fileN 10a
D libN 10a inz('*LIBL')
D DS based(pEntry)
D fieldName 1 10
D dataType 11 11
D use 12 12
D outBufPos 13 16i 0
D inBufPos 17 20i 0
D byteLeng 21 24i 0
D digits 25 28i 0
D decPos 29 32i 0
D fieldText 33 82
D editCode 83 84
D editWordLen 85 88i 0
D editWord 89 152
D colHead1 153 172
D colHead2 173 192
D colHead3 193 212
D intName 213 222
D altName 223 252
D lenAltFld 253 256i 0
D numDBCS 257 260i 0
D alwNull 261 261N
D hostVarInd 262 262N
D datTimFmt 263 266
D datTimSep 267 267
D varyingInd 268 268N
D i S 10i 0
D zonedFields S * dim(100)
D numZoned S 5p 0 inz(0)
D zonedCheck S 30a varying
C *entry plist
C fileN parm fileParm 10
C parm recordParm 10
C parm libParm 10
C if %parms > 2
C eval libN = libParm
C endif
* Get the list of all the fields
C call 'QUSLFLD'
C parm userSpace space 20
C parm 'FLDL0100' format 10
C parm filename 20
C parm recordParm 10
C parm '0' override 1
* Get a pointer to the user space containing the list
C call 'QUSPTRUS'
C parm userSpace space 20
C parm pUserSpace
* Process the list
C do numEntries i
C eval pEntry = pUserSpace + listOffset
C + ((i - 1) * entrySize)
* Store the pointer to the entry for each zoned field
C if dataType = 'S'
C eval numZoned = numZoned + 1
C eval zonedFields(numZoned) = pEntry
C endif
C enddo
* Print the header
C except header
* Process the file
C eval ovrCmd = 'OVRDBF FILE '
C + 'TOFILE('
C + %TRIM(libN)
C + '/'
C + %TRIM(fileN)
C + ')'
C call 'QCMDEXC'
C parm ovrCmd 100
C parm 100 ovrCmdLen 15 5
C open file
C read file record
C dow not %eof
C exsr process
C read file record
C enddo
C close file
C seton lr
C process begsr
C do numZoned i
C eval pEntry = zonedFields(i)
C exsr checkDDE
C enddo
C endsr
C checkDDE begsr
C eval zonedCheck = %subst(record
C : inBufPos
C : byteLeng)
C testn zonedCheck 10
C if not *in10
C except haveDDE
C endif
C endsr
Oqsysprt e header
O ' Library: '
O libN
Oqsysprt e header
O ' File: '
O fileN
Oqsysprt e header
O ' Record: '
O recordParm
Oqsysprt e header
O ' # of zoned fields: '
O numZoned J
Oqsysprt e header
O '--------------------'
O '--------------------'
O '--------------------'
O '--------------------'
Oqsysprt e haveDDE
O ' Record: '
O rrn J
O ' Field: '
O fieldName
