Cob Basics 3

8/12/2019 Cob Basics 3

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TITLE : Divisions of COBOL

Purpose:

To introduce how to declare data items in COBOL

To introduce data types in COBOL

OBJECTIVES:

Be aware of data types in COBOL

Be aware of how to declare data items in COBOL

Be aware of Picture clause

Understand grouping of data items

Declare sample record structure

Unit3


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Categories of Data

There are three categories of data item used in COBOL

programs:

Variables.

Literals. Figurative Constants

A variable is a named location in memory into which a

program can put data, and from which it can retrieve data.

A literal is a data-item that consists only of the data-item valueitself.

Figurative Constant is assigned to a data-item it fills the whole

item overwriting everything in it


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Variables

Every variable used in a COBOL program must be describedin the DATA DIVISION.

Variable declaration also defines the type of data to be stored

in the variable

In COBOL, there are really only three data types

Numeric (Only numbers)

Alphanumeric (Combination of Characters and numbers) Alphabetic (Only Characters)


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Literals

Literals are constant data-items.

There are two types of literals

String/Alphanumeric Literals

Numeric Literals

String/Alphanumeric literals are enclosed in quotes and consistof alphanumeric characters

"Michael Ryan",

Numeric literals may consist of numerals, the decimal point,

and the plus or minus sign. Numeric literals are not enclosed inquotes

123, 123.45


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Figurative Constants

SPACEor SPACES Acts like one or more spaces

ZEROor ZEROSor

ZEROES

Acts like one or more zeros

QUOTEor QUOTES Used instead of a quotationmark

HIGH-VALUEor HIGH-

VALUES

Uses the maximum value

possible

LOW-VALUEor LOW-

VALUES

Uses the minimum value

possible

ALLliteral Allows a ordinary literal to act

as Figurative Constant


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Declaring Data

In COBOL, a variable declaration consists of a line in the

DATA DIVISION that contains the following items:

A level number.

A data-name or identifier. A Picture clause.

The level-number specifies the hierarchy of data within a

record

The PICTURE clause specifies the general characteristics andediting requirements of an elementary item.


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Picture Clause

9 The digit nine is used to indicate the occurrence of a digit

at the corresponding position in the picture.X The character X is used to indicate the occurrence of any

character from the character set at the corresponding

position in the picture.

A The character A is used to indicate the occurrence of anyalphabetic character (A to Z plus blank) at the

corresponding position in the picture.

V The character V is used to indicate the position of the

decimal point in a numeric value. It is often referred to asthe "assumed decimal point".

S The character S indicates the presence of a sign and can

only appear at the beginning of a picture.


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Level Numbers

An "elementary item" is the name we use in COBOL todescribe a data-item that has not been further subdivided

Elementary items musthave a picture clause because theyactually reserve the storage required for the item. The amount

of storage reserved is specified by the item's picture clause 01 CustomerName PIC X(20)

01 GrossPay PIC 9(5)V99

A group item consists of elementary items

the hierarchical relationship between the various subordinateitems of the group is expressed using level numbers

The higher the level number, the lower the item is in thehierarchy


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Level Numbers

A group item cannot have a picture clause because it does notactually reserve any storage.

The size of a group item is the sum of the sizes of itssubordinate elementary items

The type of a group item is always assumed to be PIC X

because a group item may have several different data itemsand types subordinate to it and an X picture is the only onewhich could support such collections.

Level numbers 01 through 49 are general level numbers

Level 77's can only be used to define individual elementaryitems.

Level 88's are used to define Condition Names

Level 66's (RENAMES clause) are used to apply a new nameto an identifier or group of identifiers.


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Value Clause

The VALUE clause specifies the initial contents of a data item

If the VALUE clause is specified at the group level, the literal

must be a nonnumeric literal or a figurative constant.

01 NetPay PIC 9(5)V99 VALUE ZEROS

01 CustDiscount PIC V99 VALUE .25


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Usage Clause

The USAGE clause is used to specify how a data item is to bestored in the computer's memory

The USAGE clause may be used with any data descriptionentry except those with level numbers of 66 or 88

When the USAGE clause is declared for a group item, theusage specified is applied to every item in the group

The picture clause used for COMP or PACKED-DECIMALitems must be numeric.

When the USAGE clause is not specified at either the group orelementary level, it is assumed that the usage is DISPLAY.


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Usage Clause

PIC 9(1 to 4) 1 Word (2 Bytes)

PIC 9(5 to 9) 1 Long Word (4 Bytes)PIC 9(10 to 18) 1QuadWord (8 Bytes)


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Editing Characters

Printing of decimal points where decimal alignment is implied.

Suppression of leading zeros.

Printing of dollar signs and commas.

Printing of asterisks for check protection. Printing of plus or minus signs.

Printing of debit or credit symbols for accounting applications.

Printing of spaces or zeros as separators within fields.


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Editing Characters

The appropriate report-item that will print a decimal point willhave a PICTURE of 99.99

The edit symbol Z is used to suppress leading zeros and toreplace them with blanks or spaces.

The dollar sign and comma are placed in the positions inwhich they are desired, as in the case with decimal points.

To print a minus sign for a negative sending field, we use theedit symbol -

The edit symbols DB , for debit, or CR , for credit, may beused in place of the minus sign

The edit symbol B in a PICTURE clause of a report-item willcause a space to be inserted in the corresponding position


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Editing Characters

Sending Field Report Item

PICTURE Contents PICTURE Contents

99V99 02^38 ZZ.99 b2.38

9(4)V99 3812^34 $9,999.99 $3,812.34

S999 123 - - 999 - 123

S999 123 + 999+ 123+

S999 123 - 999CR 123CR

S999 123 - 999DB 123DB

9(9) 089743456 999BB99BB9999 089 74 3456

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Cob Basics 3