openmainframeproject · MikeBauerCA · Jul 25, 2025 · Jul 20, 2025 · Jul 21, 2025 · Jul 24, 2025
diff --git a/...ming Course #2 - Learning COBOL/COBOL Programming Course #2 - Learning COBOL.md b/...ming Course #2 - Learning COBOL/COBOL Programming Course #2 - Learning COBOL.md
@@ -2773,6 +2773,77 @@ This exercise develops skills in COBOL conditional processing, program structure
 
 **Need Help?** If you encounter difficulties, you can refer to the complete solution code `CBLC1.cobol` available in VS Code Zowe Explorer or find it on [GitHub](https://github.com/openmainframeproject/cobol-programming-course/tree/master/COBOL%20Programming%20Course%20%232%20-%20Learning%20COBOL/Labs/cbl) repository.
 
+# Case Sensitive Nature of COBOL Conditions
+
+COBOL syntax is not case-sensitive for keywords and identifiers, but string literal comparisons in conditional expressions ARE case-sensitive. This distinction between language syntax and data comparisons can lead to programming errors that cause issues when your program interacts with:
+
+- **External input data**, such as text files or database records
+- **Conditional expressions** that depend on exact string matches
+- **Third-party systems** that expect a specific case format
+
+## Why It Matters
+
+The most dangerous aspect of case sensitivity errors is that they often go unnoticed during initial testing. Programs **compile successfully**, **run without errors**, but **produce incorrect results**. These kinds of "silent failures" can persist in production systems for long periods, potentially resulting in:
+
+- Inaccurate or misleading reports
+- Logic failures (e.g., skipping conditional branches)
+- Reports that appear complete but miss values
+- Data corruption or misrouting
+
+### Real-World Example
+
+Modern COBOL treats statements like:
+`MOVE MY-NUMBER TO YOUR-NUMBER` 
+and 
+`Move my-Number to your-Number`    as **equivalent** because keywords and identifiers are case-insensitive.
+
+However, **COBOL conditions** are case-sensitive when checking **string values**:
+
+`IF USA-STATE = 'new York'` = Fails, mismatch due to case
+
+`IF USA-STATE = 'New York'` = Succeeds, case matches
+
+The comparison **fails silently** COBOL won't throw an error, but the result won't be as expected.
+
+## Lab 
+
+**Case Sensitivity in Data Comparison:**
+Understand how case sensitivity in COBOL string comparisons can cause logical errors and learn to identify and fix these issues.
+
+**Scenario:** You'll investigate why a program designed to count "New York" clients returns zero when New York clients actually exist in the input data file (id.DATA).
+
+**Required Files:**
+
+- `CBL006A.cobol` - COBOL program source
+- `CBL006AJ.jcl` - JCL job to compile and execute
+- `id.DATA` - Input data file
+
+All files are available in your VS Code Zowe Explorer.
+
+### Instructions
+
+1. Open `CBL006A.cobol` from your VS Code Zowe Explorer.
+
+    This program reads account records and counts how many clients are from `"New York"`.
+
+2. Submit the JCL job `CBL006AJ.jcl`. View the job output from the JOBS section.
+- Confirm that no syntax or runtime errors occurred.
+- Now carefully read the final line of the report. `New York Clients = 000`
+
+ ![](Images/image071.png)
+
+Ask yourself: *Is this the number of New York clients you expected?* 
+
+3. Based on your understanding, where do you think the bug lies?
+- Consider the case format of both the **comparison string** and the **actual data** from the file (id.DATA).
+4. Go and update the source code `CBL006A.cobol` . 
+- Modify the string literal in the IF condition to match the exact case format found in the data file
+5. Save your changes to `CBL006A.cobol`
+6. Recompile and resubmit the job `CBL006AJ.jcl`
+7. Verify that the report now correctly shows: `New York Clients = 005`
+
+![](Images/image072.png)
+
 \newpage
 
 # Arithmetic expressions

diff --git a/COBOL Programming Course #2 - Learning COBOL/Images/image071.png b/COBOL Programming Course #2 - Learning COBOL/Images/image071.png
diff --git a/COBOL Programming Course #2 - Learning COBOL/Images/image072.png b/COBOL Programming Course #2 - Learning COBOL/Images/image072.png
diff --git a/COBOL Programming Course #2 - Learning COBOL/Labs/cbl/CBL006A.cobol b/COBOL Programming Course #2 - Learning COBOL/Labs/cbl/CBL006A.cobol
@@ -0,0 +1,173 @@
+      *-----------------------
+       IDENTIFICATION DIVISION.
+      *-----------------------
+       PROGRAM-ID.    CBL006A
+       AUTHOR.        Otto B. Boolean.
+      *--------------------
+       ENVIRONMENT DIVISION.
+      *--------------------
+       INPUT-OUTPUT SECTION.
+       FILE-CONTROL.
+           SELECT PRINT-LINE ASSIGN TO PRTLINE.
+           SELECT ACCT-REC   ASSIGN TO ACCTREC.
+      *-------------
+       DATA DIVISION.
+      *-------------
+       FILE SECTION.
+       FD  PRINT-LINE RECORDING MODE F.
+       01  PRINT-REC.
+           05  ACCT-NO-O      PIC X(8).
+           05  FILLER         PIC X(02) VALUE SPACES.
+           05  LAST-NAME-O    PIC X(20).
+           05  FILLER         PIC X(02) VALUE SPACES.
+           05  ACCT-LIMIT-O   PIC $$,$$$,$$9.99.
+           05  FILLER         PIC X(02) VALUE SPACES.
+           05  ACCT-BALANCE-O PIC $$,$$$,$$9.99.
+           05  FILLER         PIC X(02) VALUE SPACES.
+      *
+       FD  ACCT-REC RECORDING MODE F.
+       01  ACCT-FIELDS.
+           05  ACCT-NO            PIC X(8).
+           05  ACCT-LIMIT         PIC S9(7)V99 COMP-3.
+           05  ACCT-BALANCE       PIC S9(7)V99 COMP-3.
+           05  LAST-NAME          PIC X(20).
+           05  FIRST-NAME         PIC X(15).
+           05  CLIENT-ADDR.
+               10  STREET-ADDR    PIC X(25).
+               10  CITY-COUNTY    PIC X(20).
+               10  USA-STATE      PIC X(15).
+           05  RESERVED           PIC X(7).
+           05  COMMENTS           PIC X(50).
+      *
+       WORKING-STORAGE SECTION.
+       01  FLAGS.
+           05 LASTREC          PIC X VALUE SPACE.
+      *
+      * CHANGE 1: Modified variable structure to count New York clients
+      * Original counted Virginia clients - now counts New York clients
+       01  CLIENTS-PER-STATE.
+           05 FILLER              PIC X(19) VALUE
+              'New York Clients = '.
+           05 NEWYORK-CLIENTS    PIC 9(3) VALUE ZERO.
+           05 FILLER              PIC X(59) VALUE SPACES.
+      *
+       01  HEADER-1.
+           05  FILLER         PIC X(20) VALUE 'Financial Report for'.
+           05  FILLER         PIC X(60) VALUE SPACES.
+      *
+       01  HEADER-2.
+           05  FILLER         PIC X(05) VALUE 'Year '.
+           05  HDR-YR         PIC 9(04).
+           05  FILLER         PIC X(02) VALUE SPACES.
+           05  FILLER         PIC X(06) VALUE 'Month '.
+           05  HDR-MO         PIC X(02).
+           05  FILLER         PIC X(02) VALUE SPACES.
+           05  FILLER         PIC X(04) VALUE 'Day '.
+           05  HDR-DAY        PIC X(02).
+           05  FILLER         PIC X(56) VALUE SPACES.
+      *
+       01  HEADER-3.
+           05  FILLER         PIC X(08) VALUE 'Account '.
+           05  FILLER         PIC X(02) VALUE SPACES.
+           05  FILLER         PIC X(10) VALUE 'Last Name '.
+           05  FILLER         PIC X(15) VALUE SPACES.
+           05  FILLER         PIC X(06) VALUE 'Limit '.
+           05  FILLER         PIC X(06) VALUE SPACES.
+           05  FILLER         PIC X(08) VALUE 'Balance '.
+           05  FILLER         PIC X(40) VALUE SPACES.
+      *
+       01  HEADER-4.
+           05  FILLER         PIC X(08) VALUE '--------'.
+           05  FILLER         PIC X(02) VALUE SPACES.
+           05  FILLER         PIC X(10) VALUE '----------'.
+           05  FILLER         PIC X(15) VALUE SPACES.
+           05  FILLER         PIC X(10) VALUE '----------'.
+           05  FILLER         PIC X(02) VALUE SPACES.
+           05  FILLER         PIC X(13) VALUE '-------------'.
+           05  FILLER         PIC X(40) VALUE SPACES.
+      *
+       01 WS-CURRENT-DATE-DATA.
+           05  WS-CURRENT-DATE.
+               10  WS-CURRENT-YEAR         PIC 9(04).
+               10  WS-CURRENT-MONTH        PIC 9(02).
+               10  WS-CURRENT-DAY          PIC 9(02).
+           05  WS-CURRENT-TIME.
+               10  WS-CURRENT-HOUR         PIC 9(02).
+               10  WS-CURRENT-MINUTE       PIC 9(02).
+               10  WS-CURRENT-SECOND       PIC 9(02).
+               10  WS-CURRENT-CENTISECOND  PIC 9(02).
+      *    This data layout is organized according to the ouput
+      *    format of the FUNCTION CURRENT-DATE.
+      *
+      *------------------
+       PROCEDURE DIVISION.
+      *------------------
+       OPEN-FILES.
+           OPEN INPUT  ACCT-REC.
+           OPEN OUTPUT PRINT-LINE.
+      *
+       WRITE-HEADERS.
+           MOVE FUNCTION CURRENT-DATE TO WS-CURRENT-DATE-DATA.
+      *         The CURRENT-DATE function returns an alphanumeric value
+      *         that represents the calendar date and time of day
+      *         provided by the system on which the function is
+      *         evaluated.
+           MOVE WS-CURRENT-YEAR  TO HDR-YR.
+           MOVE WS-CURRENT-MONTH TO HDR-MO.
+           MOVE WS-CURRENT-DAY   TO HDR-DAY.
+           WRITE PRINT-REC FROM HEADER-1.
+           WRITE PRINT-REC FROM HEADER-2.
+           MOVE SPACES TO PRINT-REC.
+           WRITE PRINT-REC AFTER ADVANCING 1 LINES.
+           WRITE PRINT-REC FROM HEADER-3.
+           WRITE PRINT-REC FROM HEADER-4.
+           MOVE SPACES TO PRINT-REC.
+      *
+       READ-NEXT-RECORD.
+           PERFORM READ-RECORD
+            PERFORM UNTIL LASTREC = 'Y'
+      * CHANGE 2: Updated paragraph name to reflect New York processing
+      * Original was IS-STATE-VIRGINIA, now IS-STATE-NEWYORK
+            PERFORM IS-STATE-NEWYORK
+            PERFORM WRITE-RECORD
+            PERFORM READ-RECORD
+            END-PERFORM
+           .
+      *
+       CLOSE-STOP.
+           WRITE PRINT-REC FROM CLIENTS-PER-STATE.
+           CLOSE ACCT-REC.
+           CLOSE PRINT-LINE.
+           GOBACK.
+      *
+       READ-RECORD.
+           READ ACCT-REC
+           AT END MOVE 'Y' TO LASTREC
+           END-READ.
+      *
+      * CHANGE 3: Updated paragraph name and logic to check for New York
+      * Original paragraph: IS-STATE-VIRGINIA
+      *   - Checked for 'Virginia' state
+      *   - Added to VIRGINIA-CLIENTS counter
+      * Modified paragraph: IS-STATE-NEWYORK  
+      *   - Now checks for 'New York' state
+      *   - Adds to NEWYORK-CLIENTS counter
+
+       IS-STATE-NEWYORK.
+           IF USA-STATE = 'new York' THEN
+              ADD 1 TO NEWYORK-CLIENTS
+           END-IF.
+
+      *    Boolean logic -- when the conditional expression
+      *    USA-STATE = 'New York' is true, the program
+      *    counts one more client from New York
+      *    Note -- the inclusion of the word THEN is optional
+      *    END-IF -- explicitly terminates the IF statement
+      *
+       WRITE-RECORD.
+           MOVE ACCT-NO      TO  ACCT-NO-O.
+           MOVE ACCT-LIMIT   TO  ACCT-LIMIT-O.
+           MOVE ACCT-BALANCE TO  ACCT-BALANCE-O.
+           MOVE LAST-NAME    TO  LAST-NAME-O.
+           WRITE PRINT-REC.
+      *
diff --git a/COBOL Programming Course #2 - Learning COBOL/Labs/jcl/CBL006AJ.jcl b/COBOL Programming Course #2 - Learning COBOL/Labs/jcl/CBL006AJ.jcl
@@ -0,0 +1,21 @@
+//CBL006AJ JOB 1,NOTIFY=&SYSUID
+//***************************************************/
+//* Copyright Contributors to the COBOL Programming Course
+//* SPDX-License-Identifier: CC-BY-4.0
+//***************************************************/
+//COBRUN  EXEC IGYWCL
+//COBOL.SYSIN  DD DSN=&SYSUID..CBL(CBL006A),DISP=SHR
+//LKED.SYSLMOD DD DSN=&SYSUID..LOAD(CBL006A),DISP=SHR
+//***************************************************/
+// IF RC = 0 THEN
+//***************************************************/
+//RUN     EXEC PGM=CBL006A
+//STEPLIB   DD DSN=&SYSUID..LOAD,DISP=SHR
+//ACCTREC   DD DSN=&SYSUID..DATA,DISP=SHR
+//PRTLINE   DD SYSOUT=*,OUTLIM=15000
+//SYSOUT    DD SYSOUT=*,OUTLIM=15000
+//CEEDUMP   DD DUMMY
+//SYSUDUMP  DD DUMMY
+//***************************************************/
+// ELSE
+// ENDIF