Decisions, loops and PARSE

REXX has the control structures you expect, plus PARSE, a powerful way to split text into pieces. Together they let you process lists of datasets, report lines and command output.

Decisions

IF and SELECT

if rc = 0 then say 'Clean'
else say 'Return code' rc

select
  when rc = 0 then status = 'OK'
  when rc <= 4 then status = 'WARNING'
  otherwise status = 'FAILED'
end

Loops

DO in its common forms

do i = 1 to 5
  say 'Line' i
end

do while more = 'YES'   /* test before each pass */
  ...
end

do forever
  if done then leave   /* LEAVE exits; ITERATE skips */
end

Stems: REXX's arrays

A stem is a variable ending in a dot, such as line.. By convention line.0 holds the count and line.1 to line.n hold the items. EXECIO and OUTTRAP fill stems in exactly this way.

PARSE: splitting text

PARSE VAR with a template

rec = 'PAYRUN01 JOB04512 CC 0008'
parse var rec jobname jobid . rc
say jobname rc        /* PAYRUN01 0008 */

dsn = 'PROD.PAY.MASTER'
parse var dsn hlq '.' rest
say hlq               /* PROD */

Words in the template take one word each; a period skips a word; a quoted string splits at that text. The last variable takes everything left over.

Useful built-in functions

Function	Example	Result
substr	substr('PAYROLL',1,3)	PAY
pos	pos('.', 'A.B')	2
word / words	word('A B C',2) / words('A B C')	B / 3
strip	strip(' X ')	X
length	length('JOB')	3
translate	translate('abc')	ABC
right	right(7,3,'0')	007

Decisions

Loops

Stems: REXX's arrays

PARSE: splitting text

Useful built-in functions

Common mistakes

What you will see at work

Key terms