Difference between revisions of "CLP"

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{{AN}} is an acronym for {{bu|C|ontrol}} {{bu|L|anguage}} {{bu|P|rogram}}.
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#REDIRECT [[:Category:CLP]]
 
 
Much of what we find in CLP programs are IBM Commands. [http://wiki.midrange.com/index.php/Category:Commands]  Also see [[CLP Coding Rules]] and [[:Category:Commands]].
 
 
 
As with many other languages, there are multiple versions in popular usage, such as [[CLP/400]] and [[ILE-CLP]].
 
 
 
In some realities, this is comparable to software that is the "glue" connecting higher level language programs like [[:RPG]]; data base files and their over-rides; screen and print "files" and their over-rides; and other objects with Menus ... typically when we take a menu option, we are launching a CLP program.
 
 
 
== CLP Unique Commands ==
 
 
 
Some 400 [[:Category:Commands | commands]] can ONLY be executed from within a CLP program, not from [[Command Line]].  In other programming languages, these might be called OP CODES.
 
* [[PGM]] (Program)
 
* [[ENDPGM]]
 
* [[DCL]] (Declare Variable)
 
* [[IF]]
 
* [[ELSE]]
 
* [[DO]]
 
* [[ENDDO]]
 
* [[GOTO]]
 
* [[MONMSG]]
 
 
 
== Special characters ==
 
Some characters have special meaning in CL:
 
 
 
{| class="wikitable" border="1"
 
! Symbol !! Meaning
 
|-
 
| align="center"|<nowiki>||</nowiki> || *CAT
 
|-
 
| align="center"|<nowiki>|></nowiki> || *BCAT
 
|-
 
| align="center"|<nowiki>|<</nowiki> || *TCAT
 
|-
 
| align="center"|<nowiki>=</nowiki> || *EQ
 
|-
 
| align="center"|<nowiki>></nowiki> || *GT
 
|-
 
| align="center"|<nowiki><</nowiki> || *LT
 
|-
 
| align="center"|<nowiki>>=</nowiki> || *GE
 
|-
 
| align="center"|<nowiki><=</nowiki> || *LE
 
|-
 
| align="center"|<nowiki>¬=</nowiki> || *NE
 
|-
 
| align="center"|<nowiki>¬></nowiki> || *NG
 
|-
 
| align="center"|<nowiki>¬<</nowiki> || *NL
 
|-
 
| align="center"|<nowiki>&</nowiki> || *AND
 
|-
 
| align="center"|<nowiki>|</nowiki> || *OR
 
|-
 
| align="center"|<nowiki>¬</nowiki> || *NOT
 
|}
 
 
 
Ref: CL Programming, Expressionsin CL commands
 
 
 
== Pointer use ==
 
As of V5R4, CL allows the use of pointers.  There were some problems with uninitialised pointers, and PTFs were issued.  As of 15 Feb 2008, 5722-SS1:
 
* SI28620
 
* SI28196
 
* SI27953
 
 
 
These are immediate PTFs, but you will need to re-compile any CL programs using pointers in order to get the issues fixed.
 
 
 
One can't compare a pointer to *NULL, but a clever idea is to create an unused pointer (which will be set to *NULL if the above PTFs are applied) and compare to that.  Here is a snippet from Tom L. for a CL program that performs [http://code.midrange.com/1509e4633a.html getenv] from a thread on [http://archive.midrange.com/rpg400-l/200802/msg00248.html RPG400-L].
 
 
 
dcl &pNull *ptr  /* Auto-initialized to *null */
 
if ( &pEnvVar *eq &pNull )  do
 
 
 
==Categories==
 
[[Category:Programming languages]]
 
[[Category:CLP|*]]
 

Latest revision as of 14:50, 29 October 2009

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