any questions? week 1 - 2nd lecture intro to cobol programming defining files and processing data

Any Questions?

Week 1 - 2nd Lecture

Intro to COBOL Programming

Defining Files and Processing Data

What is COBOL?

• Designed by the US defense department

• Meant to be English like for ease of maintenance

COmmon Business Oriented Language

Agenda

• How does a compiler work?

• Creating a COBOL Program

• Parts of a COBOL Program

• The Perform Statement

• Defining Files

• Defining Variables

• COBOL Verbs

Compilers

• Translate programs written by humans into Machine Language Code

directly executable code

vs

2 step translate and execute programs

ie Basic, C, C++, HTML etc.

COBOL Compiler on the iSeries

COBOL Compiler

Source Code

QCBLLESRC(PGM1)

CompiledListing(PGM1)

Program Object

(PGM1)

Steps to Create a COBOL Program

Working in the Source Physical File – QCBLLESRC (created previously)

1. Create a Source Member in the Source Physical file with the type CBLLE

2. Type in the COBOL code syntax statements using an editor i.e. RDS, SEU

3. Save & Exit

4. Compile and generate the executable code

5. Repeat 1 through 4 for each program required

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Defining Files and Processing Data

Cobol Program Structure

Common Elements

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A source program consists of

FOUR DIVISIONS

PROCEDURE DIVISION.

•Instructing the computer to work with the data

IDENTIFICATION DIVISION.

•Identifying the program

ENVIRONMENT DIVISION.

•Defining the files, peripherals, etc.

DATA DIVISION.

•Defining the variables to use in the program

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Identifying The Program

PT001F

Payroll Records

PAYREP

The Cobol Program

PRINTER FILE

Payroll Report

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IDENTIFICATION DIVISION. PROGRAM-ID. PAYREP. AUTHOR. Barake, Juan - DB344E40. * TO PRINT PAYROLL REPORT

Column 7Comment LinesIgnored by the Compiler

Column 8

To start Division, Paragraph

Identification Division

• Required– Name of the Program in the Program-ID

paragraph.

• Optional– Author– Installation– Date-Written– etc.

Identification Division(Syntax)

IDENTIFICATION DIVISION.

PROGRAM-ID. program-name.

[AUTHOR. [comment-entry] … ]

[INSTALLATION. [comment-entry] …]

[DATE-WRITTEN. [comment-entry] …]

[DATE-COMPILED. [comment-entry] …]

[SECURITY. [comment-entry] …]

Environment Division

Defines the operational environment and connecting a programs internal

file / device requirements to the physical system environment.


[ENVIRONMENT DIVISION.][CONFIGURATION SECTION.]

Identifies the computer used to write / create the program and the computer it is intended to operate / execute on.

[INPUT-OUTPUT SECTION.][FILE-CONTROL.]

Connects the programs internally declared devices / files to the operating system devices / files.

Environment Division(Syntax)

[ENVIRONMENT DIVISION.][CONFIGURATION SECTION.][SOURCE-COMPUTER. AS/400.][OBJECT-COMPUTER. AS/400.]

[INPUT-OUTPUT SECTION.][FILE-CONTROL.]

[SELECT nice-file-nameASSIGN to DISK/PRINTER/WORKSTATION- physical-

file-name.]


• INPUT-OUTPUT SECTION is only required if your program uses files.– Contains the FILE-CONTROL paragraph

• DISK

• PRINTER

• DATABASE

• WORKSTATION

• FORMATFILE

– similar to setting up file pointers

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THE ENVIRONMENTThe Data File

PT001F

Payroll Records

PAYREP

The Cobol Program

PRINTER FILE

Payroll Report

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ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT PAYROLL-FILE ASSIGN TO DATABASE-PT001F ORGANIZATION IS SEQUENTIAL.

As known to the AS400 File System

As known to the Cobol Program

Syntax can use up to 30 char names AS400 system only 10

Easier to maintain links internal cobol structure to system

Select for a Database File

Select Product-File

Assign to disk-PRODPF.

Select Product-file

Assign to database-PRODPF

Access is Sequential.

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ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT PAYROLL-FILE ASSIGN TO DATABASE-PT001F ORGANIZATION IS SEQUENTIAL.

•Data File = Collection of Records

•Each Record = One employee Info

•Records have same length (bytes)

•Records made up of fields

•Sequential means that records are organized in arrival sequence

Select Statement for a Printer (Spooled) File

Select Product-Report

assign to printer-qprint.

Select Product-Report

assign to printer-qsysprt.

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ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT PAYROLL-FILE ASSIGN TO DATABASE-PT001F ORGANIZATION IS SEQUENTIAL. SELECT PRINT-FILE

ASSIGN TO PRINTER.

•PRINT-FILE is just a user-defined name

•PRINTER is a device name

•The Cobol program will refer to PRINT -FILE

Select Statement for an Externally Described Printer FileSelect Product-Report

assign to formatfile-qsysprt.

Select Statement for a Interactive-Display-File

Select Display-File

assign to workstation-PRDSPF

organization is transaction.

Select Display-File

assign to workstation-PRDSPF-SI

organization is transaction.

Data Division

Further divided into sections

Declare / define the structure of ALL data objects used within a program.

Data Division(Syntax)

[DATA DIVISION.][FILE-SECTION.]

All objects imported into the program from external (Global) sources.

[WORKING-STORAGE SECTION.]All objects required local to the program.

[LINKAGE-SECTION.]All parameter objects (fields) received from another programs or bi-directionally passed between programs.

Bringing the Outside IN

Working Storage Section

• Field or Variables needed by the program for internal processing

• Field or variable is not part of any Input or Output.• Some examples: counters, flags, edited fields

(masks), report lines, etc.• Fields are defined the same way as in the file

section• Value clause used to initialize variables or literals

(constants) used within the program.

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OUR PRINTING LAYOUT

*...+....1....+....2....+....3....+....4....+....5....+....6....+....7.. Payroll Monthly List Juan Barake 40 $ 400.00 Mary O'Brian 375 $3,125.00 Berns, Andre 275 $1,984.00

HEADER RECORD

HEADER

DETAIL RECORD

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WORKING-STORAGE SECTION. 01 HEADING-LINE. 05 FILLER PIC X(12) VALUE 'EMPLOYEE... '. 05 FILLER PIC X(110) VALUE SPACES.

01 DETAIL-LINE. 05 FILLER PIC X(8) VALUE SPACES. 05 DET-NAME PIC X(25). 05 FILLER PIC XX VALUE SPACES. 05 DET-HOURS PIC ZZZ. 05 FILLER PIC XX VALUE SPACES. 05 DET-PAY PIC $Z,ZZZ.99. 05 FILLER PIC X(92) VALUE SPACES.

77 EOF-FLAG PIC X VALUE SPACES.

HEADING-LINE:

Temporary area to hold the print header.

HEADING-LINE:

Temporary area to hold the print header.

DETAIL-LINE:

Temporary area to hold the print fields

DETAIL-LINE:

Temporary area to hold the print fields

EOF-FLAG:

Just a variable used as a ‘loop control’ Used within the logic of the program

EOF-FLAG:

Just a variable used as a ‘loop control’ Used within the logic of the program

Defining Variables

• Zoned Decimals (or signed integers)

• Packed Decimal

• Alphabetic

• Alphanumeric

• Boolean

• Dates

• Time

• TimeStamp

Variable Data vs Constant Data

• Variable Data Changes

• Constant Data doesn’t

• Figurative Constants– ZERO, ZEROS, ZEROES– SPACES

Data Division(Syntax)

[DATA DIVISION.][FILE-SECTION.][FD nice-file-name]

[RECORD CONTAINS 99 CHARACTERS].[01 record-name.]

[05 field-names PIC ????.]

[WORKING-STORAGE SECTION.][01 field-name PIC X(10).]

[LINKAGE-SECTION.][01 ws-prog-parameters.]

[05 ws-parm-1 pic x(5).][05 ws-param-2 pic 9(6).]

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DATA DEFINITIONS

• Variable Names:

•1 to 30 characters

•Letters, digits, hyphen

•See rules in page 74 of your textbook

EMPNAME is valid

EMP NAME is invalid

EMP3NAME is valid

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DATA DEFINITIONS

• Data can be either a Constant or a Variable

• Constant are known as Literals

• Variables are known as Identifiers or Fields

• Constants can be Numeric (1, 200, -100, 1.5)

• Constants can be Alphanumeric (“CBL344 Course”)

• Variables can be keywords (Cobol defined names such as DATA) or they can be user-defined (user makes up the name such as BALANCE)

File Section

• Define the files used in the program– File Description– Record Description

• Program Described vs Externally Described.

File Section FD (file declaration)

• Label Clause– Not used often– Transmitting Data

• Block Clause– Optional– I’ve never seen it used

File Section - FD

• Records Clause– Optional– Used to double check that the record format

File Section - Record Description

• Starting at an 01 level and the subsequent field(s) detail(s) in each record

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DATA DIVISION. FILE SECTION. FD PAYROLL-FILE RECORD CONTAINS 45 CHARACTERS DATA RECORD IS EMPLOYEE-IN.

01 EMPLOYEE-IN. 05 EMP-NAME PIC X(25). 05 EMP-HOURS PIC 9(03). 05 EMP-RATE PIC 99V9 USAGE COMP-3. 05 EMP-DEP PIC X(15).

Level Numbers indicate field subordination


01 indicates the top level Located in pos 8 thru 11


Data Subordination

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The Data PICture or PIC

•Data content is internally represented by EBCDIC (IBM internal representation of data equivalent to ASCII)

•It uses a byte (8 bits) to represent a single digit, a single letter, or any special character such as #

•See the EBCDIC table in page 19 of your textbook

•The content acceptable for a variable is defined by the clause PICTURE or simply PIC

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The Data PICture or PIC

• PICture describes occurrences of each character:

•Numeric are represented by 9

•Alphanumeric is represented by X

•Alphabetic is represented by A

•S represented the sign

•$ / - represent edited characters (for output)

44







45



Elements of Data Definition

Level Number

VariableName

PICture

PICtureGroup level

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FD PRINT-FILE RECORD CONTAINS 132 CHARACTERS DATA RECORD IS PRINT-LINE. 01 PRINT-LINE PIC X(132). 01 pr-header-line-1.

03 hd1-report name pic x(20).03 filler pic x(15).03 hd2-date pic 9999b99b99.03 filler pic x(15).

01 pr-detail-line.03 filler pic x(10).03 dt1-quantity pic z(5)9-.03 filler pic xxx.03 dt1-descr pic x(30).etcetc

THE PRINTER LINE DEFINITION

Record formats

Record formats

Record formats

Optionally define the record format structure Working-Storage

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THE DATA DEFINITIONSThe Payroll File

EACH EMPLOYEE RECORD LAYOUT: Data Field Buffer Buffer Field Column Field Type Length Length Position Usage Heading EMPNAME CHAR 25 25 1 Both NAME Field text . . . . . . . . . . . . . . . : NAME Alternative name . . . . . . . . . . . . : PT001F_NAME Coded Character Set Identifier . . . . . : 37 EMPHOUR ZONED 3 0 3 26 Both HOURS Field text . . . . . . . . . . . . . . . : HOURS Alternative name . . . . . . . . . . . . : PT001F_HOURS EMPRATE PACKED 3 1 2 29 Both RATE Field text . . . . . . . . . . . . . . . : RATE Alternative name . . . . . . . . . . . . : PT001F_RATE EMPDEP CHAR 15 15 31 Both DEPARTMENT Field text . . . . . . . . . . . . . . . : DEPARTMENT Alternative name . . . . . . . . . . . . : PT001F_DEPART Coded Character Set Identifier . . . . . : 37

PT001F = PAYROLL-FILE

COPYImporting DATA DEFINITIONS into your program

LIBRARY - PF

Spoolfile printoutNote: +’s on inserted lines

FFDExternal data record format structure

Linkage Section

• Define Parameters

Variable Names

• Up to 30 Characters

• Letters, numbers and hypens (-)

• No blanks

• At least one letter

• Not a COBOL Reserved Word (see text for list of reserved words)

• Meaning full names please

Variable Name Examples

Variable Name Correct?

Cindy Laurin

BAC344

Zero

Sales%

SOL-IN

PICture Clauses(Elementary Items)

• 9 - Number

• X – Alphanumeric

• A - Alphabetic

• V - Decimal Point

PACKED-DECIMAL = COMP-3

PIC Clauses

PIC 9(3) PIC 999

PIC 9(3)V9(3)

PIC X(5)

PIC S99999 COMP-3 PIC 99999 COMP-3

Date, Time, & TimeStamp fields

01 Todays-date format of date.

01 Todays-time format of time.

01 Todays-timestamp format of timestamp.

Boolean Variables

01 IN99 pic 1.

PIC Clauses(Group Items)

• Mix of Elementary Items.

• Used to break a variable into smaller portions

PIC Clauses(Group Item – Example)

01 Student-Number PIC 9(9).

01 Student-Number-Edited.

05 Student-Number-Part-1 PIC 9(3).



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Picture Clause Review

• Define Variables

• Define how Variables are displayed

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Editing FunctionsFunction CharacterPrinting of a / as a separator /

Printing of Decimal Point in an integer .

Suppress Leading Zeros in an integer Z

Print a Dollar Sign in front of an integer $

Print a Comma in an integer ,

Printing of + or – signs + or -

Printing of ‘Debit’ or ‘Credit’ symbols DB or CR

Printing of Spaces as separators B

Printing of Zeros as separators 0

Print Leading asterix *

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Examples

Trans-Amount PIC 9(6)V999 Value 4565.78.

Report-Item Edited Results

PIC 9(6)V999

PIC $999999V999

PIC $ZZZ,ZZZ.99

PIC $ZZZ,ZZZ.9

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Examples

Trans-Amount PIC 9(6)V999 Value 4565.78.

Report-Item Edited Results

PIC $ZZZ,ZZZ.99-

PIC $ZZZ,ZZZ.99CR

PIC $ZZZZZZB99

PIC $ZZZZZZ.99+

For Next Week

• Review Reserved words in Text

• Do your assignment!

any questions? week 1 - 2nd lecture intro to cobol programming defining files and processing data

Documents

source program

file pointers

cobol programthe

cobol programworking

cobol programparts

cobol programsyntax

data division

as400 file systemas