1 chapter – 12 table lookups table codes –expanded values –types of codes numeric alphabetic...

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Chapter – 12 Table Lookups

•Table Codes–Expanded Values–Types of Codes

•Numeric•Alphabetic•Alphanumeric

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Figure 12.1 Table of Major Codes

02 ART HISTORY04 BIOLOGY19 CHEMESTRY21 CIVIL ENGINEERING24 COMP INF SYS32 ECONOMICS39 FINANCE43 MANAGEMENT49 MARKETING54 STATISTICS

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TABLE 12.1 Types of Table Codes

SYMBOLS NUMBER OF POSSIBLE VALUES

CODE TYPE USED 1 POSITION 2 POSITIONS n POSITIONS

Numeric 0 - 9 101 = 10 102 = 100 10n

Alphabetic A - Z 261 = 26 262 = 676 26n

Alphanumeric A - Z, 0 - 9 361 = 36 362 = 1,296 36n

Characteristics of Codes

• Precise - each code is unique allowing only one alternative

• Expandable - allows for future growth

• Mnemonic - easy to remember meaning of the code

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• Characteristics of codes– Percise– Mnemonic– Expandable

• Sequential table lookup– N/2 attempts– Sequential check of table entries– Organization by frequency of occurrence

• 80/20 rule

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Figure 12.2 Sequential Table Lookup

02 ART HISTORY

04 BIOLOGY

19 CHEMESTRY

21 CIVIL ENGINEERING

24 COMP INF SYS

32 ECONOMICS

39 FINANCE

43 MANAGEMENT

49 MARKETING

53 STATISTICS

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1st try

2nd try

3rd try

4th try

5th try

6th try

7th tryFINANCE

Match

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• Binary table lookup– Methodology– Speed advantages

• Positional Organization– Positional table

• Wasted space• Address is the code• Consecutive numeric codes• Direct access to table elements

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Figure 12.3Binary Lookup

02 ART HISTORY

04 BIOLOGY

19 CHEMESTRY

21 CIVIL ENGINEERING

24 COMP INF SYS

32 ECONOMICS

39 FINANCE

43 MANAGEMENT

49 MARKETING

53 STATISTICS

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1st try

FINANCEMatch

2nd try

3rd try

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TABLE 12.2 Required Number of Comparisons for Binary Search

NUMBER OF ELEMENTS MAXIMUM NUMBER OF COMPARISONS

8 - 15

16 - 31

32 - 63

64 - 127

128 - 255

256 - 511

512 - 1023

1024 - 2047

2048 - 4095

(less than 24)

(less than 25)

(less than 26)

(less than 27)

(less than 28)

(less than 29)

(less than 210)

(less than 211)

(less than 212)

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5

6

7

8

9

10

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12

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Figure 12.4 Positional Organization & Direct Lookup

02 ART HISTORY

04 BIOLOGY

19 CHEMESTRY

21 CIVIL ENGINEERING

24 COMP INF SYS

32 ECONOMICS

39 FINANCE

43 MANAGEMENT

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1st tryFINANCE Match

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• Initializing a table– Hard coding

• VALUE, REDEFINES, OCCURS

– reading from a file• Dynamically defining the size of the record

– Table Lookups• Perform Varying• Search Statement

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01 MAJOR-VALUE. 05 FILLER PIC X(10) VALUE ‘02ART HISTORY’. 05 FILLER PIC X(10) VALUE ‘04BIOLOGY’. 05 FILLER PIC X(10) VALUE ‘19CHEMISTRY’. 05 FILLER PIC X(10) VALUE ‘21CIVIL ENG’. 05 FILLER PIC X(10) VALUE ‘24COMP INF SYS’. 05 FILLER PIC X(10) VALUE ‘32ECONOMICS’. 05 FILLER PIC X(10) VALUE ‘39FINANCE’. 05 FILLER PIC X(10) VALUE ‘43MANAGEMENT’. 05 FILLER PIC X(10) VALUE ‘40MARKETING’. 05 FILLER PIC X(10) VALUE ‘54STATISTICS’.

01 MAJOR-TABLE REDEFINES MAJOR-VALUE. 05 MAJORS OCCURS 10 TIMES.

10 MAJOR-CODE PIC 9(2).10 EXPANDED-MAJOR PIC X(12).

Figure 12.5Initialization via Hard Coding

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Figure 12.6Table Initialization (Storage Schematic)

0 2 A R T H I S T O R Y 4 B I O L O G Y 0 5 4 S T A T I S T I

MAJOR-VALUE

MAJOR-TABLE

...

CD (1)EXP-MAJOR (1) CD (2) EXP-MAJOR (2) EXP-MAJOR (10)CD (10)

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Figure 12.7Input-Loaded Table

FD MAJOR-CODE-FILE. RECORD CONTAINS 14 CHARACTERS DATA RECORD IS MAJOR-CODE-RECORD.01 MAJOR-CODE-RECORD. 05 INCOMING-FILE-CODE PIC 9(2). 05 INCOMING-FILE-NAME PIC X(12).. . .WORKING-STORAGE SECTION.01 MAJOR-TABLE. 05 MAJORS OCCURS 1 TO 10 TIMES DEPENDING ON NUMBER-OF-MAJORS

INDEXED BY MAJOR-INDEX.10 MAJOR-CODE PIC 9(2).10 EXPANDED-MAJOR PIC X(12).

01 NUMBER-OF-MAJORS PIC 99 VALUE ZERO.

01 END-OF-MAJOR-FILE-SW PIC X VALUE SPACES. 88 END-OF-MAJOR-FILE VALUE ‘Y’.

(a) Data Division entries

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Figure 12.7 Input-Loaded Table

PROCEDURE DIVISION.OPEN INPUT MAJOR-CODE-FILE.PERFORM VARYING MAJOR-INDEX FROM 1 BY 1 UNTIL MAJOR-INDEX > 10

OR END-OF-MAJOR-FILE READ MAJOR-CODE-FILE

AT END MOVE ‘Y’ TO END-OF-MAJOR-FILENOT AT END ADD 1 TO NUMBER-OF-MAJORS MOVE INCOMING-FILE-CODE TO MAJOR-CODE (MAJOR-INDEX) MOVE INCOMING-FILE-NAME TO EXPANDED-MAJOR (MAJOR-INDEX)

END-READEND-PERFORM.IF MAJOR-INDEX > 10 DISPLAY ‘MAJOR TABLE TOO SMALL’END-IF.CLOSE MAJOR-CODE-FILE

PERFORM 0100-PREPARE-STUDENT-TRANSCRIPT.. . .

(b) In-Line Perform

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• How many unique codes can be developed from a 4 position

numeric code, alphabetic code, 4 position alphanumeric code.

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What’s wrong with this code?

01 MONTH-TABLE.05 MONTH OCCURS 12 TIMES PIC X(4).

05 MONTH-VALUES REDEFINES MONTH PIC X(36)

VALUE ‘JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC’.

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• Table Lookups– Using the PERFORM .. VARYING statement– Using the SEARCH statement

• Must use indexes

– Using the SEARCH ALL statement• Uses index plus codes must be in order• Uses a binary search• Does not use a set command

– Direct lookup• Positional table

– Range-step tables• No one-to-one correspondence

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19CHEMISTRY

Figure 12.8Input-Loaded Tables

04BIOLOGY

02ART HISTORY

02 ART HISTORY 04 BIOLOGY 19 CHEMISTRY

MAJOR-CODE (1)

EXPANDED-MAJOR (1)

MAJOR-CODE (2)

EXPANDED-MAJOR (2)

MAJOR-CODE (3)

EXPANDED-MAJOR (3)

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Figure 12.9 Sequential Lookup with PERFORM VARYING

WORKING-STORAGE SECTION.01 TABLE-PROCESSING-ELEMENTS. 05 WS-MAJOR-SUB PIC S9(4) COMP. 05 WS-FOUND-MAJOR-SWITCH PIC X(3) VALUE ‘NO’. 05 WS-END-OF-TABLE-SWITCH PIC X(3) VALUE ‘NO’.

01 MAJOR-VALUE. 05 FILLER PIC X(10) VALUE ‘02ART HISTORY’. 05 FILLER PIC X(10) VALUE ‘04BIOLOGY’. 05 FILLER PIC X(10) VALUE ‘19CHEMISTRY’. 05 FILLER PIC X(10) VALUE ‘21CIVIL ENG’. 05 FILLER PIC X(10) VALUE ‘24COMP INF SYS’. 05 FILLER PIC X(10) VALUE ‘32ECONOMICS’. 05 FILLER PIC X(10) VALUE ‘39FINANCE’. 05 FILLER PIC X(10) VALUE ‘43MANAGEMENT’. 05 FILLER PIC X(10) VALUE ‘40MARKETING’. 05 FILLER PIC X(10) VALUE ‘54STATISTICS’.

01 MAJOR-TABLE REDEFINES MAJOR-VALUE. 05 MAJORS OCCURS 10 TIMES.

10 MAJOR-CODE PIC 9(2).10 EXPANDED-MAJOR PIC X(12).

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Figure 12.9 Sequential Lookup with PERFORM VARYING

PROCEDURE DIVISION.0000-PREPARE-STUDENT-REPORT. MOVE ‘NO’ TO WS-FOUND-SWITCH

WS-END-OF-TABLE-SWITCH. PERFORM 1000-FIND-MAJOR

VARYING WS-MAJOR-SUB FROM 1 BY 1 UNTIL WS-END-OF-TABLE-SWITCH = ‘YES’ OR WS-FOUND-MAJOR-SWITCH = ‘YES’.

. . .1000-FIND-MAJOR. IF WS-MAJOR-SUB > 10

MOVE ‘YES’ TO WS-END-OF-TABLE-SWITCHMOVE ‘UNKNOWN’ TO HDG-MAJOR

ELSEIF ST-MAJ0R-CODE = MAJOR-CODE (WS-MAJOR-SUB) MOVE ‘YES’ TO WS-FOUND-MAJOR-SWITCH MOVE EXP-MAJOR (WS-MAJOR-SUB) TO HDG-MAJOREND-IF

END-IF.

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Figure 12.10 SEARCH Statement (Sequential Lookup)

01 MAJOR-VALUE. 05 FILLER PIC X(10) VALUE ‘02ART HISTORY’. 05 FILLER PIC X(10) VALUE ‘04BIOLOGY’. 05 FILLER PIC X(10) VALUE ‘19CHEMISTRY’. 05 FILLER PIC X(10) VALUE ‘21CIVIL ENG’. 05 FILLER PIC X(10) VALUE ‘24COMP INF SYS’. 05 FILLER PIC X(10) VALUE ‘32ECONOMICS’. 05 FILLER PIC X(10) VALUE ‘39FINANCE’. 05 FILLER PIC X(10) VALUE ‘43MANAGEMENT’. 05 FILLER PIC X(10) VALUE ‘40MARKETING’. 05 FILLER PIC X(10) VALUE ‘54STATISTICS’.

01 MAJOR-TABLE REDEFINES MAJOR-VALUE. 05 MAJORS OCCURS 10 TIMES INDEXED BY MAJOR-INDEX.

10 MAJOR-CODE PIC 9(2).10 EXPANDED-MAJOR PIC X(12).

. . .

INDEXED BY clause required in table definition

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Figure 12.10 SEARCH Statement (Sequential Lookup)

PROCEDURE DIVISION.. .

.SET MAJOR-INDEX TO 1.SEARCH MAJORS

AT END MOVE ‘UNKNOWN’ TO HDG-MAJORWHEN ST-MAJOR-CODE = MAJOR-CODE (MAJOR-INDEX) MOVE EXP-MAJOR (MAJOR-INDEX) TO HDG-MAJOR

END-SEARCH.

SET statement establishes starting point

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Figure 12.11 SEARCH ALL Statement (Binary Lookup)

KEY required for binary search (ASCENDING or DESCENDING)

01 MAJOR-VALUE. 05 FILLER PIC X(10) VALUE ‘02ART HISTORY’. 05 FILLER PIC X(10) VALUE ‘04BIOLOGY’. 05 FILLER PIC X(10) VALUE ‘19CHEMISTRY’. 05 FILLER PIC X(10) VALUE ‘21CIVIL ENG’. 05 FILLER PIC X(10) VALUE ‘24COMP INF SYS’. 05 FILLER PIC X(10) VALUE ‘32ECONOMICS’. 05 FILLER PIC X(10) VALUE ‘39FINANCE’. 05 FILLER PIC X(10) VALUE ‘43MANAGEMENT’. 05 FILLER PIC X(10) VALUE ‘40MARKETING’. 05 FILLER PIC X(10) VALUE ‘54STATISTICS’.

01 MAJOR-TABLE REDEFINES MAJOR-VALUE. 05 MAJORS OCCURS 10 TIMES ASCENDING KEY IS MAJOR-CODE INDEXED BY MAJOR-INDEX.

10 MAJOR-CODE PIC 9(2).10 EXPANDED-MAJOR PIC X(12).

. . .

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Figure 12.11 SEARCH ALL Statement (Binary Lookup)

PROCEDURE DIVISION.. .

.SEARCH ALL MAJORS

AT END MOVE ‘UNKNOWN’ TO HDG-MAJORWHEN MAJOR-CODE (MAJOR-INDEX) = ST-MAJOR-CODE

MOVE EXP-MAJOR (MAJOR-INDEX) TO HDG-MAJOREND-SEARCH.

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Figure 12.12 Direct Access to Table Entries01 MAJOR-VALUE. 05 FILLER PIC X(12) VALUE ‘UNKNOWN’. 05 FILLER PIC X(12) VALUE ‘ACCOUNTING’.

05 FILLER PIC X(12) VALUE ‘UNKNOWN’. 05 FILLER PIC X(12) VALUE ‘BIOLOGY’. .

. .

05 FILLER PIC X(12) VALUE ‘STATISTICS’.

01 MAJOR-TABLE REDEFINES MAJOR-VALUE. 05 MAJORS OCCURS 54 TIMES PIC X(12). . . .PROCEDURE DIVISION. . . . IF ST-MAJOR-CODE > 0 AND ST-MAJOR-CODE < 55

MOVE MAJORS (ST-MAJOR-CODE) TO HDG-MAJOR ELSE

MOVE ‘UNKNOWN’ TO HDG-MAJOR END-IF.

Positional organizationresults in wasted space

Check to ensure valid code

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Figure 12.13 Range-step TableGrade Point Scholarship Average Percentage

3.75 - 4.00 100 3.50 - 3.74 75

3.25 - 3.49 503.00 - 3.24 332.75 - 2.99 252.50 - 2.74 15

(a) Scholarship Table

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Figure 12.13 Range-step Table01 SCHOLARSHIP-TABLE. 05 GPA-SCHOLARSHIP-PERCENTAGES. 10 FILLER PIC X(6) VALUE ‘375100’. 10 FILLER PIC X(6) VALUE ‘350075’. 10 FILLER PIC X(6) VALUE ‘325050’. 10 FILLER PIC X(6) VALUE ‘300033’. 10 FILLER PIC X(6) VALUE ‘275025’. 10 FILLER PIC X(6) VALUE ‘250015’.

05 GPA-TABLE REDEFINES GPA-SCHOLARSHIP-PERCENTAGES OCCURS 6 TIMES INDEXED BY GPA-INDEX. 10 GPA-MINIMUM PIC 9V99. 10 SCHOLARSHIP-PCT PIC 999.. . . SET GPA-INDEX TO 1. SEARCH GPA-TABLE AT END

MOVE ZERO TO SCHOLARSHIP-AWARD WHEN STUDENT-GPA >= GPA-MINIMUM (GPA-INDEX)

MOVE SCHOLARSHIP-PCT (GPA-INDEX) TO SCHOLARSHIP-AWARD END-SEARCH.

(b) COBOL Implementation

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Summary

•Codes & types•VALUE, OCCURS, & REDEFINES used to define and initialize a table.•Table lookups – sequential, binary, direct access•Range-step table•Tables are initialized by hard-coding or dynamically loading at execution time•SEARCH statement, requires an index•SEARCH ALL statement, index & in order