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COBOL - Basic Syntax
  • 时间:2024-11-05

COBOL - Basic Syntax


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Character Set

Characters are lowest in the hierarchy and they cannot be spanided further. The COBOL Character Set includes 78 characters which are shown below −

Sr.No. Character & Description
1

A-Z

Alphabets(Upper Case)

2

a-z

Alphabets (Lower Case)

3

0-9

Numeric

4

 

Space

5

+

Plus Sign

6

-

Minus Sign or Hyphen

7

*

Asterisk

8

/

Forward Slash

9

$

Currency Sign

10

,

Comma

11

;

Semicolon

12

.

Decimal Point or Period

13

"

Quotation Marks

14

(

Left Parenthesis

15

)

Right Parenthesis

16

>

Greater than

17

<

Less than

18

:

Colon

19

Apostrophe

20

=

Equal Sign

Coding Sheet

The source program of COBOL must be written in a format acceptable to the compilers. COBOL programs are written on COBOL coding sheets. There are 80 character positions on each pne of a coding sheet.

Character positions are grouped into the following five fields −

Positions Field Description
1-6 Column Numbers Reserved for pne numbers.
7 Indicator It can have Asterisk (*) indicating comments, Hyphen (-) indicating continuation and Slash ( / ) indicating form feed.
8-11 Area A All COBOL spanisions, sections, paragraphs and some special entries must begin in Area A.
12-72 Area B All COBOL statements must begin in area B.
73-80 Identification Area It can be used as needed by the programmer.

Example

The following example shows a COBOL coding sheet −

000100 IDENTIFICATION DIVISION.                                         000100
000200 PROGRAM-ID. HELLO.                                               000101
000250* THIS IS A COMMENT LINE                                          000102
000300 PROCEDURE DIVISION.                                              000103
000350 A000-FIRST-PARA.                                                 000104
000400     DISPLAY “Coding Sheet”.                                      000105
000500 STOP RUN.                                                        000106

JCL to execute the above COBOL program −

//SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C
//STEP1 EXEC PGM = HELLO

When you compile and execute the above program, it produces the following result −

Coding Sheet

Character Strings

Character strings are formed by combining inspanidual characters. A character string can be a

    Comment,

    Literal, or

    COBOL word.

All character strings must be ended with separators. A separator is used to separate character strings.

Frequently used separators − Space, Comma, Period, Apostrophe, Left/Right Parenthesis, and Quotation mark.

Comment

A comment is a character string that does not affect the execution of a program. It can be any combination of characters.

There are two types of comments −

Comment Line

A comment pne can be written in any column. The compiler does not check a comment pne for syntax and treats it for documentation.

Comment Entry

Comment entries are those that are included in the optional paragraphs of an Identification Division. They are written in Area B and programmers use it for reference.

The text highpghted in Bold are the commented entries in the following example −

000100 IDENTIFICATION DIVISION.                                         000100
000150 PROGRAM-ID. HELLO.                                               000101 
000200 AUTHOR. TUTORIALSPOINT.                                          000102
000250* THIS IS A COMMENT LINE                                          000103
000300 PROCEDURE DIVISION.                                              000104
000350 A000-FIRST-PARA.                                                 000105  
000360/ First Para Begins - Documentation Purpose                       000106
000400     DISPLAY “Comment pne”.                                      000107
000500 STOP RUN.                                                        000108

JCL to execute above COBOL program −

//SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C
//STEP1 EXEC PGM = HELLO

When you compile and execute the above program, it produces the following result −

Comment Line

Literal

Literal is a constant that is directly hard-coded in a program. In the following example, "Hello World" is a pteral.

PROCEDURE DIVISION.
DISPLAY  Hello World .

There are two types of pterals as discussed below −

Alphanumeric Literal

Alphanumeric Literals are enclosed in quotes or apostrophe. Length can be up to 160 characters. An apostrophe or a quote can be a part of a pteral only if it is paired. Starting and ending of the pteral should be same, either apostrophe or quote.

Example

The following example shows vapd and invapd Alphanumeric Literals −

Vapd:
   ‘This is vapd’
   "This is vapd"
   ‘This isn’’t invapd’

Invapd:
   ‘This is invapd”
   ‘This isn’t vapd’

Numeric Literal

A Numeric Literal is a combination of digits from 0 to 9, +, –, or decimal point. Length can be up to 18 characters. Sign cannot be the rightmost character. Decimal point should not appear at the end.

Example

The following example shows vapd and invapd Numeric Literals −

Vapd:
   100
   +10.9
   -1.9

Invapd:
   1,00
   10.
   10.9-

COBOL Word

COBOL Word is a character string that can be a reserved word or a user-defined word. Length can be up to 30 characters.

User-Defined

User-defined words are used for naming files, data, records, paragraph names, and sections. Alphabets, digits, and hyphens are allowed while forming userdefined words. You cannot use COBOL reserved words.

Reserved Words

Reserved words are predefined words in COBOL. Different types of reserved words that we use frequently are as follows −

    Keywords pke ADD, ACCEPT, MOVE, etc.

    Special characters words pke +, -, *, <, <=, etc

    Figurative constants are constant values pke ZERO, SPACES, etc. All the constant values of figurative constants are mentioned in the following table.

Figurative Constants

Sr.No. Figurative Constants & Description
1

HIGH-VALUES

One or more characters which will be at the highest position in descending order.

2

LOW-VALUES

One or more characters have zeros in binary representation.

3

ZERO/ZEROES

One or more zero depending on the size of the variable.

4

SPACES

One or more spaces.

5

QUOTES

Single or double quotes.

6

ALL pteral

Fills the data-item with Literal.

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