CL Programming.pdf

Objectives

Explain general programming concepts

Explain CL’s strengths and weaknesses

as a programming language

Show how to create a CL program

Explain what a compilation report is and

how to use it to find program errors

2

Creating CL Programs

Library

PF-SRC

CRTMBR

CLP

Compile

CRTMBR

*PGM

CLP

SEU

Programmer

CL

Commands

3

Program Processing

Programs can execute instructions

3 ways

The default method is sequential,

I.e. in statement number order

Execution can also be conditional

and iterative.

4

CL Command Syntax

The format for a CL Command is:

There is at least one space between

the:

Command

First parameter

Each succeeding parameter

Commands are continued from one

line to another by placing a plus sign

after the command or a parameter

COMMAND PARAMETER PARAMETER ….

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CL Command Syntax The + must be preceded by at least a

space if the continuation is between:

a command and a parameter

two parameters

COMMAND +

PARAMETER PARAMETER

COMMAND+

PARAMETER PARAMETER

COMMAND PARAMETER PARAMETER +

PARAMETER PARAMETER +

PARAMETER

COMMAND PARAMETER PARAMETER+

PARAMETER PARAMETER6

Continuing a CL Command

COMM+

AND PARAMETER PARMETER

COMMAND PARAMETER PARA+

METER

COMM +

AND PARAMETER PARMETER

COMMAND PARAMETER PARA +

METER

The + is not preceded by space(s) if the

continuation is in the middle of the:

Command word

Parameter keyword

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If a parameter value(s) allows

spaces, then the + is preceded by

space(s)

GRTOBJAUT OBJ(YOURLIBXX/CLSRC) OBJTYPE(*FILE) +

USER(INTRO35) AUT(*OBJALTER *OBJEXIST +

*OBJMGT *OBJOPR *OBJREF *ADD)

SNDMSG MSG('The rain in Spain falls manely on the +

lions.') TOUSR(INTRO99)

8


If the continuation is in the middle of

a value, no spaces precede the +


USER(INTRO35) AUT(*OBJALTER *OB+

JEXIST *OBJMGT *OBJOPR *OBJREF *ADD)


USER(INTRO35) AUT(*OBJALTER *OB +

JEXIST *OBJMGT *OBJOPR *OBJREF *ADD)

9

CL Programs

Begin with a PGM command and end

with an ENDPGM command

Comments (non-executable text) may

precede the PGM statement

Comments begin with a forward slash

& an asterisk and end with an asterisk

& a forward slash

/* This is an example of a comment. */

10

Programs Programs read and write data

Data can come from storage, the OS,

or the person who calls the program

Programs can write data to storage, a

printer or a workstation

Program

Storage

Operating

System

User

PrintoutData

Data Data

Data

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User Supplied Program Data

You can supply data when calling the

program as follows:

To receive the data, the program must

have a PARM keyword in the PGM

statement.

The PARM keyword identifies the

program variables that will hold the data

CALL pgm1 (‘chardata’ numeric ‘chardata’….)

PGM PARM(&CUSTNAME &ORDAMT)

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User Supplied Program Data The parameters specified on the call

must match the parameters specified in

the PARM keyword

If they don’t match:

CALL pgm1 (‘Walmart’ 275)

PGM PARM(&CUSTNAME &ORDAMT)

CALL pgm1 (275)

Parameters passed on CALL do not match those required.

The program will not be run and you will

get the following message:

13

Program Variables

Programs store input and output in

program variables

Just like a data base field, a program

variable has a:

Name

Length

Data type

Program variables exist for as long as

the program is running

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CL Program Variables Are defined with a DCL (declare)

command

A CL program variable name must:

Begin with an ampersand (&)

Has a max length of 11

Cannot contain spaces

DCL statements must be at the

beginning of the program following the

PGM statement

*************** Beginning of data **********************

0001.00 PGM PARM(&CUSTNAME &ORDAMT)

0002.00 DCL VAR(&CUSTNAME) TYPE(*CHAR) LEN(15)

0003.00 DCL VAR(&ORDAMT) TYPE(*DEC) LEN(9 2)15

Retrieving Data from OS/400 RTVSYSVAL - retrieves and stores system

parameter values in program variables:

Date

Time

System Default Printer

RTVJOBA - retrieves and stores job

information in program variables:

Job name

User running job

Output queue

RTVSYSVAL SYSVAL(QTIME) RTNVAR(&CURTIME)

RTVJOBA USER(&USERID) 16

Sending Data to a User

SNDUSRMSG - sends a message to the

person running the program or a specified

users message queue

You can build complex messages

combining static text and program variables

by using string functions

SNDUSRMSG MSG('I''ll be back')

SNDUSRMSG MSG(&CUSTNAME) MSGTYPE(*INFO) +

TOUSR(INTRO99)

17

String Functions

Concatenation - joins two strings together

*CAT

*TCAT - eliminates trailing spaces

*BCAT - one trailing space between strings

Results in:

SNDUSRMSG MSG('I''ll be back at ’ *CAT &CURTIME)

SNDUSRMSG MSG('I''ll be back at ’ *TCAT &CURTIME)

SNDUSRMSG MSG('I''ll be back at ’ *BCAT &CURTIME)

I'll be back at 14:09:08

I'll be back at14:09:08

I'll be back at 14:09:08

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String Functions

Substring - identifies a subset of a string

%SST(string start-location size)

When used with a CHGVAR command,

new strings can be created.

Results in:

CHGVAR VAR(&NOSECTIME) VALUE(%SST(&CURTIME 1 5)

SNDUSRMSG MSG('I''ll be back at ’ *BCAT &NOSECTIME)

I'll be back at 14:09

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CL Program0001.00 START: PGM PARM(&LIBNAME &FILENAME &MEMNAME &MEMTYPE)

0002.00

0003.00 /* Create info is supplied and the variables defined*/

0004.00

0005.00 DCL VAR(&FILENAME) TYPE(*CHAR) LEN(10)

0006.00 DCL VAR(&MEMNAME) TYPE(*CHAR) LEN(10)

0007.00 DCL VAR(&LIBNAME) TYPE(*CHAR) LEN(10)

0008.00 DCL VAR(&MEMTYPE) TYPE(*CHAR) LEN(3)

0009.00

0010.00 /* The member is created */

0011.00

0012.00 CRTMBR: STRSEU SRCFILE(&LIBNAME/&FILENAME) +

0013.00 SRCMBR(&MEMNAME) +

0014.00 TYPE(&MEMTYPE)

0015.00

0016.00 /* Message to confirm member creation is sent */

0017.00

0018.00 SNDUSRMSG MSG('IT''S DONE, PAPPY!')

0019.00

0020.00 /* The program is ended */

0021.00

0022.00 END: ENDPGM 20

Compilation Reports

Library

PF-SRC

CRTMBR

CLPCompile

CRTMBR

*PGM

CLP

Compilation

Report

MSGQ

21

Compilation Reports

General Information

Source Code Listing

Cross reference table

Error message summary

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General information area Display Spooled File

File . . . . . : COMPILEEX Page/Line 1/1

Control . . . . . ________ Columns 1 - 78

Find . . . . . . ______________________________

*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...

5763SS1 V3R2M0 960517 Control Language GRA

Program . . . . . . . . . . . . . . . . . . . : COMPILEEX

Library . . . . . . . . . . . . . . . . . . : GRADES

Source file . . . . . . . . . . . . . . . . . : GRADES

Library . . . . . . . . . . . . . . . . . . : GRADES

Source member name . . . . . . . . . . . . . : COMPILEEX 10/30/97 17:06:

Source printing options . . . . . . . . . . . : *SOURCE *XREF *GEN *NOSE

Program generation options . . . . . . . . . : *NOLIST *NOXREF *NOPATCH

User profile . . . . . . . . . . . . . . . . : *USER

Program logging . . . . . . . . . . . . . . . : *JOB

Allow RTVCLSRC command . . . . . . . . . . . : *YES

Replace program . . . . . . . . . . . . . . . : *YES

Target release . . . . . . . . . . . . . . . : V3R2M0

Authority . . . . . . . . . . . . . . . . . . : *LIBCRTAUT

Sort sequence . . . . . . . . . . . . . . . . : *HEX

Language identifier . . . . . . . . . . . . . : *JOBRUN

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Searching the report

Control field commands provide quick

movement through the spool file

P+5 Move forward 5 pages

P-5 Move backwards 5 pages

P5 Move to page 5

+5 Move forward 5 lines

-5 Move backwards 5 lines

W+5 Move to the right 5 columns

W-5 Move to the left 5 columns

W5 Move to the fifth column

B or *BOT Move to the end of the spool file

T or *TOP Move to the beginning of the spool file

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Find Area

Allows you to search for a character

string within the compilation report

Case sensitive

To find a string:

Enter the text in the find area

Press F16

To find other occurrences of the

string continue to press F16

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Source Code Listing Displays source code

Error messages placed after incorrect

statements

Control Language Source

SEQNBR *...+... 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+...

100- DCL VAR(&JOB) TYPE(*CHAR) LEN(7)

* CPD0740 10 PGM command missing.

200- DCL VAR(&USR) TYPE(*CHAR) LEN(10)

300- RTVJOBA JOB(&JOB)

* CPD0784 30 Variable &JOB for parameter JOB must be *CHAR, minimum length 10

400- RTVJOBA USER(&USER)

* CPD0727 40 Variable '&USER ' is referred to but not declared.

500- SNDUSRMSG MSG('The job number is' *cat &job *cat +

600 'and the user is ' *cat &user *cat +

700 '.') TOUSR(&USER)



800- GOTO CMDLBL(END)

* CPD0725 10 End of source file reached without ENDPGM command.

* * * * * E N D O F S O U R C E * * * *

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Error messages

Comprised of three parts:

Error code

Error message

Severity level

CPD0740 10 PGM command missing.

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Cross Reference table For every variable and label, the statement

numbers that reference each are displayed

Errors messages listed here also

5763SS1 V3R2M0 960517 Control Language GRA

Cross Reference

Declared Variables

Name Defined Type Length References

&JOB 100 *CHAR 7 300 500

&USR 200 *CHAR 10

* CPD0726 10 Variable '&USR ' declared but not referred to.

Defined Labels

Label Defined References

END ****** 800

* CPD0715 30 Label 'END ' does not exist.

* * * * * E N D O F C R O S S R E F E R E N C E

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Error Message Summary Error message total

Subtotals by severity level

Successful or not message

Max severity

Message Summary

Severity

Total 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90

8 0 3 0 2 3 0 0 0 0

Program COMPILEEX not created in library GRADES. Maximum error severity 40.

* * * * * E N D O F M E S S A G E S U M

Severity 20 errors (and higher) stop the compile29

Run Time Errors

Source code that compiles can still

have errors when run or have

incorrect output

If there is a run time error, the system

will display a short message

For more info about the problem:

Move the cursor to the message

Press F1

Additional Message Information will

be displayed for the message

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JOBLOG

Most of the time, Additional Message

Information will be enough to

understand the problem

If not, all messages need to be

checked. (Not just the one displayed

by the system.)

Display the JOBLOG by

Pressing F10 at the Additional

Message Information screen

Or issue the DSPJOBLOG command

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Run Time Errors

Some run time errors are not the

result of incorrect programming e.g.

Incorrect user input

Lack of authority

No data

The program should not end when

these types of errors occur

The program should check for these

conditions and provide user friendly

messages

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Monitoring for Messages

MONMSG - allows the program, NOT the

OS, to handle specified message(s)

The CL command specified in the EXEC

keyword is executed when the error occurs

If MONMSG placed right after DCL’s:

EXEC performed regardless of the program

statement causing the error

If MONMSG follows a command:

EXEC performed only if the preceding

command caused the specified error

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Monitoring for Messages

CPF9810 - library does not exist

CPF9812 - file does not exist

This MONMSG results in an error

handling routine being executed

No EXEC keyword means the error

will be ignored

MONMSG MSGID(CPF9810) EXEC(CRTLIB &LIBNAME)

MONMSG MSGID(CPF9812) EXEC(GOTO CMDLBL(NOFILE))

MONMSG MSGID(CPF9812)

34

Error Handling Routines

Can further investigate the cause of

the problem

Perform complex functions to solve

the problem

Allow the user to select a course of

action from program defined options

35

Message Replies

Messages can be sent that require

a reply

The reply can be stored in a

program variable

The reply value can be the basis for

conditional statement execution

36

Message Replies MSGRPY - Identifies the program

variable to hold the reply

VALUES - Defines the valid values that

can be entered as a reply

IF condition - if true, the statement(s)

following THEN will be performed

MONMSG MSGID(CPF9810) EXEC(SNDUSRMSG MSG('THE LIBRARY +

SPECIFIED DOES NOT EXIST. TO CREATE THE LIBRARY, REPLY +

WITH A "Y". TO END THE PROGRAM, REPLY WITH A "N".') +

MSGRPY(&REPLY) VALUES(Y N))

IF COND(&REPLY *EQ N) THEN(GOTO END)

IF COND(&REPLY *EQ Y) THEN(CRTLIB &LIBNAME)

37

Points to Remember

CL commands can be “grouped” into

programs

Compilation reports are used to

diagnose compile errors

The JOBLOG helps diagnose run time

errors

Users can create their own CL

commands

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Documents

CL Programming.pdf