Lesson 6

05 NUMERIC-FIELDPIC 9(5). 05 ALPHANUMERIC-FIELDPIC X(5).... IF NUMERIC-FIELD = 10...(valid entry) IF NUMERIC-FIELD = ‘10’... (invalid entry) IF ALPHANUMERIC-FIELD = 10(invalid entry) IF ALPHANUMERIC-FIELD = ‘10’(valid entry) The Relational Condition (a) Syntax (b) Examples IS [NOT] GREATER THAN IS [NOT] > IS [NOT] LESS THAN identifier-1IS [NOT] = IS [NOT] LESS THAN OR EQUAL TO IS [NOT] <=

CONDITION? STATEMENT2 STATEMENT1 STATEMENT3 CONDITION? STATEMENT1 STATEMENT2 The IF Statement (a) With ELSE Option (b) Without ELSE Option FALSE TRUE

The ELSE Clause/II A=B MOVE ZERO TO C MOVE 1 TO C WRITE DETAIL-LINE MOVE ZERO TO D MOVE 1 TO D FALSETRUE IF A = B MOVE 1 TO C MOVE 1 TO D ELSE MOVE ZERO TO C MOVE ZERO TO D END-IF. WRITE DETAIL-LINE. (a) IF/ELSE Flowchart(b) COBOL Code

Nested IF Statements/II C>D? ADD 1 TO Y ADD 1 TO X A>B? FALSE TRUE IF A > B IF C > D ADD 1 TO X ELSE NEXT SENTENCE ELSE ADD 1 TO Y. IF A > B IF C > D ADD 1 TO X END-IF ELSE ADD 1 TO Y END-IF (b) NEXT SENTENCE (COBOL-74) (c) Scope Terminators (COBOL-85) (a) Flowchart

IBM COBOL Reference Manual: ‘The presence of one or more IF statements within the initial IF statement constitutes a "nested IF statement." Nesting statements is much like specifying subordinate arithmetic expressions enclosed in parentheses and combined in larger arithmetic expressions.’ Nested IF’s

IF A = B NEXT SENTENCE ELSE PERFORM D0-ARITHMETIC-CALCULATIONS END-IF. IF condition A = B is true then NEXT SENTENCE is executed and the ELSE phrase is ignored, and control passes to the statement following the END-IF.

The Class Test NUMERIC ALPHABETIC IF identifier IS [NOT]ALPHABETIC-UPPER ALPHABETIC-LOWER (a) Syntax 05 NUMERIC-FIELDPIC 9(5). 05 ALPHABETIC-FIELDPIC X(5).... IF NUMERIC-FIELD IS NUMERIC PERFORM D0-ARITHMETIC-CALCULATIONS END-IF. IF NUMERIC-FIELD IS NOT NUMERIC DISPLAY ‘ERROR - NUMERIC FIELD CONTAINS INVALID DATA’ END-IF. IF ALPHABETIC-FIELD IS ALPHABETIC DISPLAY ‘ALPHABETIC FIELD CONTAINS UPPER AND/OR LOWER CASE LETTERS’ END-IF. IF ALPHABETIC-FIELD IS NOTALPHABETIC DISPLAY ‘ERROR - ALPHABETIC FIELD CONTAINS NON-ALPHABETIC DATA’ END-IF. (b) Examples

The SignTest identifierPOSITIVE IF arithmetic expression IS [NOT]NEGATIVE ZERO (a) Syntax IF NET-PAY IS NOT POSITIVE PERFORM TOO-MUCH-TAXES END-IF. IF CHECK-BALANCE IS NEGATIVE PERFORM OVERDRAWN END-IF. (b) Examples

Condition Names (88-level entries) (a) Syntax 05 YEAR-CODEPIC FRESHMANVALUE SOPHOMOREVALUE JUNIORVALUE SENIORVALUE GRAD-STUDENTVALUES ARE 5 THRU UNDER-CLASSMANVALUES ARE 1, 2 88 UPPER-CLASSMANVALUES ARE 3, VALID-CODESVALUES ARE 1 THRU 8. IF FRESHMAN PERFORM WELCOME-NEW-STUDENTS END-IF IF VALID-CODES PERFORM PROCESS-STUDENT-RECORD ELSE DISPLAY ‘INCOMING YEAR CODE IS IN ERROR’ END-IF. (b) Examples VALUE ISTHROUGH 88 data-name VALUES AREliteral-1 THRU literal-2...

Level 88 Identifies any condition-name entry that is associated with a particular value of a conditional variable. Check sample code (program CPCH13B)

The ACCEPT Statement WORKING-STORAGE SECTION. 01 EMPLOYEE-RECORD EMP-DATE-OF-BIRTH. 10 EMP-BIRTH-MONTHPIC EMP-BIRTH-YEARPIC EMPLOYEE-AGEPIC 99V DATE-WORK-AREA. 05 TODAYS-YEARPIC TODAYS-MONTHPIC TODAYS-DAYPIC PROCEDURE DIVISION... ACCEPT DATE-WORK-AREA FROM DATE... COMPUTE EMPLOYEE-AGE = TODAYS-YEAR - EMP-BIRTH-YEAR + (TODAYS-MONTH - EMP-BIRTH-MONTH) / 12.