Chapter 9 – More on Procedure
Division
• PERFORM
– TEST BEFORE/TEST AFTER
– Inline Perform
• not calling a procedure
– Performing Sections
• can be a paragraph or a section
– paragraph - one or more sentances
– section - one or more paragraphs
Figure 9.1
The Iteration Structure
A
TRUE
CONDITION?
A
FALSE
CONDITION?
FALSE
TRUE
(a) DO WHILE Construct
(b) DO UNTIL Construct
Figure 9.2
Structure of a COBOL Program
READ INPUT-FILE
AT END MOVE ‘NO’ TO DATA-REMAINS-SWITCH.
PERFORM PROCESS-RECORDS
UNTIL DATA-REMAINS-SWITCH = ‘NO’.
PROCESS-RECORDS.
.
Procedure Division statements to process the current record
.
.
READ INPUT-FILE
AT END MOVE ‘NO’ TO DATA-REMAINS-SWITCH.
(a) Priming Read
PERFORM UNTIL DATA-REMAINS-SWITCH = ‘NO’
READ INPUT-FILE
AT END
MOVE ‘NO’ TO DATA-REMAINS-SWITCH
NOT AT END
.
Procedure Division statements to process the current record
.
.
END-READ
END-PERFORM.
(b) False Condition Branch with In-Line Perform
• PERFORM THRU
– executes statements between procedure
names.
– PERFORM PROCESS1 THRU PROCESS4
• READ
– False Condition Branch
• NOT AT END
• way to avoid the priming read
– READ INTO
• read data into 2 places, working storage and
the I/O area.
• WRITE FORM
– same as READ INTO but used for writing a
record.
WRITE HEADING-LINE FROM WS-PRINT-LINE =
MOVE WS-PRINT-LINE TO HEADING-LINE
WRITE HEADING-LINE
• String Processing
– INSPECT - find/replace
– STRING - joins strings
– UNSTRING - splits strings
Figure 9.3
The READ INTO statement
FD
EMPLOYEE-FILE
DATA RECORD IS EMPLOYEE-RECORD.
01 EMPLOYEE-RECORD
PIC X(60).
.
.
.
WORKING-STORAGE SECTION.
01 FILLER
PIC X(14) VALUE ‘WS BEGINS HERE’.
01 WS-EMPLOYEE-RECORD.
05 EMP-NAME
PIC X(25).
.
.
.
PROCEDURE DIVISION.
.
.
.
READ EMPLOYEE-FILE INTO WS-EMPLOYEE-RECORD
AT END
MOVE ‘NO’ TO DATA-REMAINS-SWITCH
NOT AT END
PERFORM PROCESS-THIS-RECORD
END-READ.
Figure 9.4
The INSPECT statement
01
RECORD-IN.
05 SOC-SEC-NUM
.
.
.
01 PRINT-LINE.
05 SOC-SEC-NUM-OUT
.
.
.
PIC 9(9).
PIC 999B99B9999.
PROCEDURE DIVISION.
.
.
.
MOVE SOC-SEC-NUM TO SOC-NUM-OUT.
INSPECT SOC-SEC-NUM-OUT REPLACING ALL ‘ ‘ BY ‘-’.
Initial:
SOC-SEC-NUM
123 45 6789
Result:
SOC-SEC-NUM-OUT
123-45-6789
Figure 9.5
The STRING Statement
05 NAME-IN-PIECES.
10 LAST-NAME
10 FIRST-NAME
10 MIDDLE-INITIAL
PIC X(16).
PIC X(10).
PIC X.
05 ENTIRE-NAME
PIC X(29).
(a) Working-Storage Holding Areas
Before Execution
LAST-NAME
SM I T H
MIDDLE-INITIAL
H
FIRST-NAME
J OHN
ENTIRE-NAME
Figure 9.5
The STRING Statement (cont.)
MOVE SPACES TO ENTIRE-NAME.
STRING FIRST-NAME DELIMITED BY SPACE
‘ ‘ DELIMITED BY SIZE
MIDDLE-INITIAL DELIMITED BY SPACE
‘ ‘ DELIMITED BY SIZE
LAST-NAME DELIMITED BY SPACE
INTO ENTIRE-NAME
(b) STRING Statement
Execution Steps
(1) ENTIRE-NAME
J OHN
(2) ENTIRE-NAME
J O H N (b)
(3) ENTIRE-NAME
J O H N (b) H
(4) ENTIRE-NAME
J O H N (b) H (b)
(5) ENTIRE-NAME
J O H N (b) H (b) S M I T H
(c) Sequence of transfer
Figure 9.6
The UNSTRING Statement
05 NAME-IN-PIECES.
10 LAST-NAME
10 FIRST-NAME
10 MIDDLE-INITIAL
PIC X(16).
PIC X(10).
PIC X.
05 ENTIRE-NAME
PIC X(31).
(a) Working-Storage Holding Areas
MOVE SPACES TO NAME-IN-PIECES.
UNSTRING ENTIRE-NAME DELIMITED BY ‘ ‘
INTO FIRST-NAME MIDDLE-INITIAL LAST-NAME.
(b) UNSTRING Statement
Before Execution
LAST-NAME
MIDDLE-INITIAL
FIRST-NAME
ENTIRE-NAME
J O H N (b) H (b) S M I T H
Figure 9.6
The UNSTRING Statement
(1) ENTIRE-NAME
J O H N (b) H (b) S M I T H
(1) ENTIRE-NAME
J O H N (b) H (b) S M I T H
J OHN
FIRST-NAME
H
SM I T H
MIDDLE-INITIAL
LAST-NAME
(c) Execution of UNSTRING
The WRITE FROM statement
FD PRINT-FILE
DATA RECORD IS PRINT-LINE.
01 PRINT-LINE
PIC X(80).
PROCEDURE DIVISION.
.
.
MOVE HEADING-LINE TO PRINT-LINE.
WRITE PRINT-LINE
AFTER ADVANCING PAGE.
(a) Two instruction process
FD PRINT-FILE
DATA RECORD IS PRINT-LINE.
01 PRINT-LINE
PIC X(80).
.
.
01 HEADING-LINE.
03
PIC X(17) VALUE SPACES.
03
PIC X(25)
VALUE ‘ INVENTORY REPORT PREPARED BY GARPL’.
PROCEDURE DIVISION.
.
.
WRITE PRINT-LINE FROM HEADING-LINE
AFTER ADVANCING PAGE.
(b) One instruction process
• INITALIZE
– 01 GROUP-ITEM
• 05 NUMERIC-FIELD
PIC 9(4)
• 05 ALPHANUMERIC-FIELD PIC X(15)
INITIALIZE GROUP-ITEM ==
MOVE ZEROS TO NUMERIC-FIELD
MOVE SPAES TO ALPHANUMERIC-FIELD
INITIALIZE GROUP-ITEM REPLACING
NUMERIC BY ZERO ==
MOVE ZEROS TO NUMERIC-FIELD
The INITIALIZE statement
• Sets elementary or group data names to ‘initial’ value
• DOES NOT RESET VALUE TO THAT OF THE VALUE STATEMENT!!!
• EX:
01 GROUP-ITEM.
05 NUMERIC-FIELD-1
05 NUMERIC-FIELD-2
05 ALPHANUMERIC-FIELD-1
05 ALPHANUMERIC-FIELD-2
• The statement
PIC 9(4).
PIC 9(4).
PIC X(15).
PIC X(20).
INITIALIZE GROUP-ITEM
• is equivalent to the combined statements:
MOVE ZEROS TO NUMERIC-FIELD-1.
MOVE ZEROS TO NUMERIC-FIELD-2.
MOVE SPACES TO ALPHANUMERIC-FIELD-1.
MOVE SPACES TO ALPHANUMERIC-FIELD-2.
• ACCEPT
• Duplicate Data Names
– Qualification
– MOVE CORRESPONDING
• The Car billing program
– Program design
– The Completed Program