Basics of COBOL

COBOL (COMMON BUSINESS ORIENTED LANGUAGE) : COBOL (COMMON BUSINESS ORIENTED LANGUAGE) Overview

COBOL Fundamentals : COBOL Fundamentals DAY1

Session Plan : Session Plan Day 1: Introduction to COBOL Evolution, Features & Language Fundamentals Program Structure Data description entry

References : References M.K.Roy and D. Ghosh Dastidar, COBOL Programming, Tata McGraw Hill, New York, 1973. Nancy Stern and Robert Stern, COBOL Programming, John Wiley & Sons, New York, 1973. Newcomer and Lawrence, Programming with Structured COBOL, McGraw Hill Books, New York, 1973.

History of COBOL : 1959 – United States Department of Defense 1960 - COBOL initial specifications presented by CODASYL (Conference on Data Systems Languages) 1964 – BASIC COBOL extended to Visual COBOL 1968 – ANSI (American National Standards Institute) developed American National Standard (ANS) COBOL 1974 – ANSI published revised version of (ANS) COBOL – Business applications needed to manipulate character as well as numeric data – String operations added 1985 – COBOL 85 Standards was introduced with revised version of COBOL-74. History of COBOL

COBOL : What does COBOL stand for? COmmon Business Oriented Language. Which are target area of COBOL applications? Defense, Aircraft, Insurance, Finance, Retail etc (file & data oriented applications involved) So we can say that COBOL is basically used for writing business applications and not for developing system software COBOL

Slide 7 : COBOL – Program Structure Principal portions of a program. There are 4 divisions – Identification (Required) Environment (Optional) Data (Optional) Procedure (Required) User defined chunk of code which consists of one/more paragraphs. e.g. a) U000-CHECK-LOG SECTION. b) FILE SECTION. User defined chunk of code which consists of one/more sentences. e.g. a) P000-PRINT-FINAL-TOTALS. b) PROGRAM-ID. A SENTENCE consists of one or more statements and is terminated by a full stop. e.g. a) MOVE .21 TO VAT-RATEb) COMPUTE VAT-AMOUNT = PRODUCT-COST * VAT-RATE. PROGRAM DIVISIONS SECTIONS PARAGRAPHS SENTENCES STATEMENTS A STATEMENT consists of a COBOL verb and an operand or operands. e.g. SUBTRACT T-TAX FROM GROSS-PAY GIVING NET-PAY CHARACTERS RESERVED WORDS USER DEFINED WORDS

COBOL CHARACTER SET : COBOL CHARACTER SET Overview

Slide 9 :

Slide 10 : IDENTIFICATION DIVISION. PROGRAM-ID. PROG1. AUTHOR. R.R. BHATT. INSTALLATION. ABC CORP. DATE-WRITTEN. 01-JAN-2005. DATE-COMPILED. 01-JAN-2005. SECURITY. HIGH. OPTIONAL Compiler takes this as Program Identifier. PROGRAM-ID comes immediately after ID Division. IDENTIFICATION DIVISION …

Slide 11 : ENVIRONMENT DIVISION CONFIGURATION SECTION INPUT-OUTPUTT SECTION Identifies the computer used for compiling of programs Identifies the resources used for executing the program ENVIRONMENT DIVISION

Slide 12 : The DATA DIVISION is used to describe the data structures used in the program. There are sections in the DATA DIVISION FILE SECTION WORKING-STORAGE SECTION LINKAGE SECTION REPORT SECTION The two most commonly used components (sections) are a) WORKING-STORAGE SECTION Internal data structures are defined here. b) FILE SECTION File I/O buffer areas are defined here. DATA DIVISION

DATA DIVISION : DATA DIVISION. FILE SECTION. FD INVENTORY-FILE RECORD CONTAINS 78 CHARACTERS. 01 INVENTORY-REC. 05 IF-PART-NUMBER PIC X(09). 05 PIC X(24). 05 IF-WHSE-LOCS. 10 IF-MAIN-LOC PIC X(06). 10 IF-ALT-LOC PIC X(06). 05 PIC X(33). FD PRINT-FILE. 01 PRINT-REC. 05 PIC X(10). 05 P-PART-NUMBER PIC X(09). 05 PIC X(05). 05 P-MAIN-LOC PIC X(06). 05 PIC X(05). 05 P-ALT-LOC PIC X(06). WORKING-STORAGE SECTION. 01 FLAGS. 05 F-MORE-RECORDS PIC X VALUE 'Y'. DATA DIVISION

PROCEDURE DIVISION .. : The PROCEDURE DIVISION consists of the following – Sections Paragraphs Sentences Statements PROCEDURE DIVISION ..

PROCEDURE DIVISION : PROCEDURE DIVISION PROCEDURE DIVISION. 0001-ACCOUNT-SECTION. 001-ACCOUNT-READ-PARA. READ ACC-FILE AT END MOVE ‘Y’ TO EOF. MOVE TAX-REDUCT TO TAX-AMOUNT 001-ACCOUNT-VALIDATE-PARA. ADD AMOUNT TO TOT-AMOUNT. ACCEPT EMPLOYEE-SALARY DISPLAY “Current Employee Salary “ EMPLOYEE-SALARY. 001-EXIT-PARA. STOP RUN. Section Paragraph Sentences statement Section contain one or more Paragraphs. A PARAGRAPH comprises of one or more sentences A SENTENCE is a combination of one or more statements and is terminated by a full stop. A STATEMENT is a combination of a COBOL verb and one or more operands.

First COBOL program : IDENTIFICATION DIVISION. PROGRAM-ID. FIRSTPG. PROCEDURE DIVISION. A0000-MAIN-PARA. DISPLAY ‘-------------------------------’. DISPLAY ‘ WELCOME TO COBOL’. DISPLAY ‘--------------------------------’. STOP RUN. First COBOL program

COBOL coding sheet : COBOL coding sheet

COBOL coding sheet : Almost all COBOL compilers treat a line of COBOL code as if it contained two distinct areas. These are - AREA A *) Between Column 8 to 11 *) Division, Section, Paragraph names, FD entries & 01 level entries must start in Area A AREA B *) Between Column 12 to 72 *) All Sentences & Statements start in Area B COBOL coding sheet

COBOL coding rules : Each line is considered to be made up of 80 columns. Columns 1 to 6 are reserved for line numbers.Column 7 is an indicator column and has specialmeaning to the compiler. Asterisk ( * ) indicates comments Hyphen ( - ) indicates continuation Slash ( / ) indicates form feed Columns 8 to 11 are called Area A. All COBOL DIVISIONs, SECTIONs, paragraphs and some special entries must begin in Area A. Columns 12 to 72 are called Area B. All COBOL statements must begin in Area B. Columns 73 to 80 are identification area. COBOL coding rules

Basic data types : Basic data types Alphabetic ( A) Numeric( 9) Alphanumeric (X) Edited numeric ( Z, $) Edited alphanumeric(/,-)

Data names : Are named memory locations. Must be described in the DATA DIVISION before they can be used in the PROCEDURE DIVISION. Can be of elementary or group type. Can be subscripted for Arrays. Are user defined words . Data names

Rules for forming User-defined words : Can be at most 30 characters in length. Only alphabets, digits and hyphen are allowed. Blanks are not allowed. May not begin or end with a hyphen. Should not be a COBOL reserved word like ADD,SUBTRACT,MOVE,DISPLAY etc…. Rules for forming User-defined words

Description of data names : All the data names used in the PROCEDURE DIVISION must be described in the DATA DIVISION. The description of a data name is done with the aid of the following – (1) Level number (2) PICTURE clause (3) VALUE clause Description of data names DATA DIVISION. 01 WS-EMPL-NO PIC X(10) VALUE 1001. LEVEL NO Data Name Picture Clause VALUE Clause

DATA NAME ? LEVEL NO : Is used to specify the the data hierarchy. Level number Level Number Purpose 01 Record description and independent items 02 to 49 Fields within records and sub items 66 RENAMES clause 77 Independent items 88 Condition names DATA NAME ? LEVEL NO

Piture Clause : Code Meaning 9 Numeric A Alphabetic X Alphanumeric V Implicit Decimal S Sign bit Piture Clause PICTURE clause

COBOL ‘PICTURE’ Clauses : COBOL ‘PICTURE’ Clauses Some examples PICTURE 999 a three digit (+ive only) integer PICTURE S999 a three digit (+ive/-ive) integer PICTURE XXXX a four character text item or string PICTURE 99V99 a +ive ‘real’ in the range 0 to 99.99 PICTURE S9V9 a +ive/-ive ‘real’ in the range ? If you wish you can use the abbreviation PIC. Numeric values can have a maximum of 18 (eighteen) digits (i.e. 9’s). The limit on string values is usually system-dependent.

Abbreviating recurring symbols : Abbreviating recurring symbols Recurring symbols can be specified using a ‘repeat’ factor inside round brackets PIC 9(6) is equivalent to PICTURE 999999 PIC 9(6)V99 is equivalent to PIC 999999V99 PICTURE X(10) is equivalent to PIC XXXXXXXXXX PIC S9(4)V9(4) is equivalent to PIC S9999V9999 PIC 9(18) is equivalent to PIC 999999999999999999

Declaring DATA in COBOL : Declaring DATA in COBOL In COBOL a variable declaration consists of a line containing the following items; Œ A level number.  A data-name or identifier. Ž A PICTURE clause. We can give a starting value to variables by means of an extension to the picture clause called the value clause.

Description of data names .. : VALUE clause Is used to assign an initial value to a elementary data item. The initial value can be numeric literal, non- numeric literal or figurative constant. Is an optional clause. Description of data names ..

Literals : Literals are symbols whose value does not change in a program. There are 3 types of literals namely (1) Numeric literals. (2) Non-numeric literals. (3) Figurative constants. Literals

Literals – Figurative Constants : Figurative constants Meaning ZERO(S) or ZEROES Represents the value 0, one or more depending on the context SPACE(S) Represents one or more spaces HIGH-VALUE(S) Represents the highest value LOW-VALUE(S) Represents the lowest value QUOTE(S) Represents single or double quotes ALL literal Fill With Literal Literals – Figurative Constants

Figurative Constants - Examples : Figurative Constants - Examples 01 StudentName PIC X(10) VALUE "MIKE". MOVE ALL "-" TO StudentName. GrossPay 0 0 0 1 3 5 0 ñ l

Figurative Constants - Examples : Figurative Constants - Examples 01 StudentName PIC X(10) VALUE "MIKE". MOVE ALL "-" TO StudentName. GrossPay 0 0 0 0 0 0 0 ñ l

Group and elementary items : In COBOL the term “group item” is used to describe a data item which has been further subdivided. A Group item is declared using a level number and a data name. It cannot have a picture clause. Where a group item is the highest item in a data hierarchy it is referred to as a record and uses the level number 01. Picture clauses are NOT specified for ‘group’ data items because the size of a group item is the sum of the sizes of its subordinate, elementary items and its type is always assumed to be PIC X. Group and elementary items WORKING-STORAGE SECTION. 01 EMPLOYEE-DETAILS PIC X(30). 01 EMPLOYEE-DETAILS. 05 EMP-NUM PIC 9(4). 05 EMP-NAME PIC X(10). 05 EMP-DEPT PIC X(4). 05 EMP-LOC PIC X(12).

Group Items/Records - Example : WORKING-STORAGE SECTION. 01 EMPLOYEE-DETAILS PIC X(20). 01 EMPLOYEE-DETAILS. 05 EMP-NUM PIC 9(4). 05 EMP-NAME PIC X(10). 05 EMP-DEPT PIC X(4). 05 EMP-LOC PIC X(12). Group item Sub-Items Group Items/Records - Example

Group Items/Records - Example : 123456789012345678901234567890 (cols) 1234JyothiS E&R Bangalore 2234Archana E&R Marathi 9999Bhushan E&R C++ Data in input file WORKING-STORAGE SECTION. 01 EMPLOYEE-DETAILS PIC X(30). 1234JyothiS E&R Bangalore Variable for file read Value Group Items/Records - Example

Group Items/Records - Example : WORKING-STORAGE SECTION. 01 EMPLOYEE-DETAILS PIC X(30). 01 EMPLOYEE-DETAILS. 05 EMP-NUM PIC 9(4). 05 EMP-NAME PIC X(10). 05 EMP-DEPT PIC X(4). 05 EMP-LOC PIC X(12). 1234JyothiS E&R Bangalore 1234 JyothiS E&R Bangalore Variable for file read Value 123456789012345678901234567890 (cols) 1234JyothiS E&R Bangalore 2234Archana E&R Mysore 9999Bhushan E&R Chennai Data in input file Group Items/Records - Example

LEVEL Numbers & DATA hierarchy : In COBOL, Level numbers are used to express data hierarchy. The higher the level number, the lower the item is in the hierarchy. So Group items contain sets of elementary items with lower level numbers. At the lowest level the data is completely atomic. LEVEL Numbers & DATA hierarchy WORKING-STORAGE SECTION. 01 POLICY-DETAILS. 05 POLICY-NO. 10 POLICY-TYP PIC X(4). 10 POLICY-LOC PIC X(2). 10 POLICY-ID PIC X(5). 05 POLICY-TYPE PIC X(10). 05 POLICY-EXPDT PIC X(10).

Description of data names : DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-REGNO PIC X(5). 01 WS-NAME. 05 WS-FIRST-NAME PIC A(15). 05 WS-MID-NAME PIC A(15). 05 WS-LAST-NAME PIC A(10). 01 WS-AGE PIC 99V99. 01 WS-SCHOLARSHIP PIC 9(4) VALUE 1000. Description of data names

Group Items/Records : H E N N E S S Y R M 9 2 3 0 1 6 5 L M 5 1 0 5 5 0 F Group Items/Records StudentDetails WORKING-STORAGE SECTION. 01 StudentDetails PIC X(26).

Group Items/Records : H E N N E S S Y R M 9 2 3 0 1 6 5 L M 5 1 0 5 5 0 F StudentDetails StudentName StudentId CourseCode Grant Gender Group Items/Records WORKING-STORAGE SECTION. 01 StudentDetails. 02 StudentName PIC X(10). 02 StudentId PIC 9(7). 02 CourseCode PIC X(4). 02 Grant PIC 9(4). 02 Gender PIC X.

Group Items/Records : H E N N E S S Y R M 9 2 3 0 1 6 5 L M 5 1 0 5 5 0 F StudentDetails Surname Initials WORKING-STORAGE SECTION. 01 StudentDetails. 02 StudentName. 03 Surname PIC X(8). 03 Initials PIC XX. 02 StudentId PIC 9(7). 02 CourseCode PIC X(4). 02 Grant PIC 9(4). 02 Gender PIC X. StudentName StudentId CourseCode Grant Gender Group Items/Records

MOVE VERB : MOVE VERB Overview

The MOVE Verb : The MOVE Verb MOVE copies data from the source identifier or literal to one or more destination identifiers. MOVE copies data to Group or elementary data items. MOVE always performs LEFT JUSTIFICATION to Character MOVE always perform RIGHT JUSTIFICATION to Numeric data. When data is MOVEd into an item the contents of the item are completely replaced. If the source data is too small to fill the destination item entirely the remaining area is zero or space filled.

MOVEing Data : MOVE “RYAN” TO Surname. MOVE “FITZPATRICK” TO Surname. 01 Surname PIC X(8). MOVEing Data C O U G H L A N

MOVEing Data : R Y A N MOVE “RYAN” TO Surname. MOVE “FITZPATRICK” TO Surname. 01 Surname PIC X(8). MOVEing Data

MOVEing Data : MOVE “RYAN” TO Surname. MOVE “FITZPATRICK” TO Surname. 01 Surname PIC X(8). MOVEing Data F I T Z P A T R I C K

MOVEing to a numeric item. : MOVEing to a numeric item. When the destination item is numeric, or edited numeric, then data is aligned along the decimal point with zero filling or truncation as necessary. When the decimal point is not explicitly specified in either the source or destination items, the item is treated as if it had an assumed decimal point immediately after its rightmost character.

Slide 49 : MOVE ZEROS TO GrossPay. MOVE 12.4 TO GrossPay. MOVE 123.456 TO GrossPay. MOVE 12345.757 TO GrossPay. 01 GrossPay PIC 9(4)V99. 0 0 0 0 0 0 0 0 1 2 4 0 0 1 2 3 4 5 6 1 2 3 4 5 7 5 7 ñ l ñ l ñ l ñ l GrossPay GrossPay GrossPay GrossPay

Slide 50 : MOVE 1234 TO CountyPop. MOVE 12.4 TO CountyPop. MOVE 154 TO Price. MOVE 3552.75 TO Price. 01 CountyPop PIC 999. 01 Price PIC 999V99. ñ l 1 2 3 4 0 1 2 4 1 5 4 0 0 3 5 5 2 7 5 ñ l Price CountyPop ñ l ñ l CountyPop Price

Slide 51 : Before WS00-OUT1 0000 WS00-OUT2 000000 After WS00-OUT1 3456 WS00-OUT2 345678 Before WS00-OUT3 000000 After WS00-OUT3 123456 Before WS00-OUT4 00000000 After WS00-OUT4 12345678

Slide 52 : MOVE .. example **************************** WS00-OUT1 : HARAYANA WS00-OUT2 : HARAYANA **************************** Output SPOOL

The DISPLAY Verb : The DISPLAY Verb From time to time it may be useful to display messages and data values on the screen. A simple DISPLAY statement can be used to achieve this. A single DISPLAY can be used to display several data items or literals or any combination of these. The WITH NO ADVANCING clause suppresses the carriage return/line feed.

The ACCEPT verb : The ACCEPT verb 01 CurrentDate PIC 9(6). * YYMMDD 01 DayOfYear PIC 9(5). * YYDDD 01 Day0fWeek PIC 9. * D (1=Monday) 01 CurrentTime PIC 9(8). * HHMMSSss s = S/100

Slide 55 : PROCEDURE DIVISION. Begin. DISPLAY "Enter student details using template below". DISPLAY "NNNNNNNNNNSSSSSSSCCCCGGGGS ". ACCEPT StudentDetails. ACCEPT CurrentDate FROM DATE. ACCEPT DayOfYear FROM DAY. ACCEPT CurrentTime FROM TIME. DISPLAY "Name is ", Initials SPACE Surname. DISPLAY "Date is " CurrentDay SPACE CurrentMonth SPACE CurrentYear. DISPLAY "Today is day " YearDay " of the year". DISPLAY "The time is " CurrentHour ":" CurrentMinute. STOP RUN. IDENTIFICATION DIVISION. PROGRAM-ID. AcceptAndDisplay. AUTHOR. Michael Coughlan. DATA DIVISION. WORKING-STORAGE SECTION. 01 StudentDetails. 02 StudentName. 03 Surname PIC X(8). 03 Initials PIC XX. 02 StudentId PIC 9(7). 02 CourseCode PIC X(4). 02 Grant PIC 9(4). 02 Gender PIC X. 01 CurrentDate. 02 CurrentYear PIC 99. 02 CurrentMonth PIC 99. 02 CurrentDay PIC 99. 01 DayOfYear. 02 FILLER PIC 99. 02 YearDay PIC 9(3). 01 CurrentTime. 02 CurrentHour PIC 99. 02 CurrentMinute PIC 99. 02 FILLER PIC 9(4).

Example Program - Date : Example Program - Date Overview