When coding a program, there will be several situations where you might want to perform logical operations using Boolean items. COBOL enables this using Boolean expressions.
000010 @OPTIONS MAIN 000020*---------------------------------------------------------------------- 000030* Boolean expressions are used for operations using Boolean data items. 000040*---------------------------------------------------------------------- 000050 IDENTIFICATION DIVISION. 000060 PROGRAM-ID. SAMPLE. 000070 DATA DIVISION. 000080 WORKING-STORAGE SECTION. 000090 01 IN-DATA PIC S9(4) COMP-5. 000100 01 CNT PIC S9(4) COMP-5. 000110 01 . 000120 02 RESULT PIC 1(12) BIT VALUE ALL B"0". 000130 02 RES-BIT REDEFINES RESULT OCCURS 12 PIC 1(1) BIT. 000140 CONSTANT SECTION. 000150 01 ELM-TBL. 000160 02 PIC X(10) VALUE "USA". 000170 02 PIC X(10) VALUE "Korea". 000180 02 PIC X(10) VALUE "Germany". 000190 02 PIC X(10) VALUE "Russia". 000200 02 PIC X(10) VALUE "England". 000210 02 PIC X(10) VALUE "Japan". 000220 02 PIC X(10) VALUE "Spain". 000230 02 PIC X(10) VALUE "France". 000240 02 PIC X(10) VALUE "Kenya". 000250 02 PIC X(10) VALUE "China". 000260 02 PIC X(10) VALUE "Brazil". 000270 02 PIC X(10) VALUE "Italy". 000280 01 REDEFINES ELM-TBL. 000290 02 ELM-NAME PIC X(10) OCCURS 12. 000300*---------------------------------------------------------------------- 000310* The category information of each country is defined using Boolean 000315* expressions. 000320* UNSC: The resident country of the United Nations is set to 1. 000330* NATO: The member nations of NATO are set to 1. 000340*---------------------------------------------------------------------- 000350 01 SUBSET-TBL. 000360 02 UNSC PIC 1(12) BIT VALUE B"100110010100". 000370 02 NATO PIC 1(12) BIT VALUE B"101010110001". 000380*---------------------------------------------------------------------- 000390 PROCEDURE DIVISION. 000400 DISPLAY "The following countries are categorized.". 000410 PERFORM TEST BEFORE 000420 VARYING CNT FROM 1 BY 1 UNTIL CNT > 12 000430 IF CNT = 6 OR 12 THEN 000440 DISPLAY ELM-NAME(CNT) 000450 ELSE 000460 DISPLAY ELM-NAME(CNT) WITH NO ADVANCING 000470 END-IF 000480 END-PERFORM. 000490 DISPLAY " ". 000500 DISPLAY "<Category>". 000510 DISPLAY "Resident country of the United Nations :1". 000520 DISPLAY "Member nations of NATO :2".
000530 DISPLAY "Countries of 1 and 2 :3". 000540 DISPLAY "Countries of neither :4". 000550 DISPLAY " ". 000560 DISPLAY "Please select the category. >>" WITH NO ADVANCING. 000570 ACCEPT IN-DATA. 000580*---------------------------------------------------------------------- 000590* Boolean operators such as AND and OR can be used to obtain the 000600* countries that match the conditions. Expressions that use these 000605* Boolean operators are referred to as Boolean expressions. 000610*---------------------------------------------------------------------- 000620 EVALUATE IN-DATA 000630 WHEN 1 COMPUTE RESULT = UNSC 000640 WHEN 2 COMPUTE RESULT = NATO 000650 WHEN 3 COMPUTE RESULT = UNSC AND NATO 000660 WHEN 4 COMPUTE RESULT = NOT (UNSC OR NATO) 000670 END-EVALUATE. 000680*---------------------------------------------------------------------- 000690 PERFORM TEST BEFORE 000700 VARYING CNT FROM 1 BY 1 UNTIL CNT > 12 000710 IF RES-BIT(CNT) = B"1" THEN 000720 DISPLAY ELM-NAME(CNT) 000730 END-IF 000740 END-PERFORM. 000750 END PROGRAM SAMPLE.
