Day 19: COBOL String Handling – Manipulating and Formatting Text Data Effectively

 


1. Introduction: Why String Handling Is Essential in COBOL

While COBOL is known for its strength in numerical and business data processing, string handling is equally important. Real-world business applications deal with vast amounts of textual data — names, addresses, product descriptions, invoice details, etc.

COBOL provides a robust set of string manipulation verbs to make text processing efficient and readable. These verbs help you:

  • Combine multiple text fields into one (e.g., name + surname)

  • Extract specific parts of a string (e.g., area code from a phone number)

  • Validate or clean data before storing it in files or reports

Some of COBOL’s most commonly used string operations include:

  • STRING – Combines multiple fields.

  • UNSTRING – Splits one string into multiple fields.

  • INSPECT – Analyzes or replaces characters in a string.

Understanding these will help you handle almost any textual transformation required in a COBOL application.

2. Example: Using STRING, UNSTRING, and INSPECT in COBOL

Here’s a hands-on example demonstrating all three key string operations.

Program: STRHANDLE.cbl

IDENTIFICATION DIVISION.
PROGRAM-ID. STRHANDLE.

DATA DIVISION.
WORKING-STORAGE SECTION.
01 FIRST-NAME      PIC A(10) VALUE "ALICE".
01 LAST-NAME       PIC A(10) VALUE "BROWN".
01 FULL-NAME       PIC A(25).
01 ADDRESS         PIC X(40) VALUE "123, MAIN STREET, NEW YORK".
01 STREET          PIC X(20).
01 CITY            PIC X(20).
01 SAMPLE-TEXT     PIC X(30) VALUE "HELLO COBOL WORLD".
01 COUNT-RESULT    PIC 9(3).

PROCEDURE DIVISION.
    DISPLAY "----- STRING OPERATION -----"
    STRING FIRST-NAME DELIMITED BY SPACE
           " " DELIMITED BY SIZE
           LAST-NAME DELIMITED BY SPACE
           INTO FULL-NAME
    END-STRING
    DISPLAY "FULL NAME: " FULL-NAME

    DISPLAY "----- UNSTRING OPERATION -----"
    UNSTRING ADDRESS DELIMITED BY ","
        INTO STREET, CITY
    END-UNSTRING
    DISPLAY "STREET: " STREET
    DISPLAY "CITY: " CITY

    DISPLAY "----- INSPECT OPERATION -----"
    INSPECT SAMPLE-TEXT TALLYING COUNT-RESULT FOR ALL "O"
    DISPLAY "NUMBER OF 'O's: " COUNT-RESULT
    INSPECT SAMPLE-TEXT REPLACING ALL "O" BY "0"
    DISPLAY "MODIFIED TEXT: " SAMPLE-TEXT
STOP RUN.

Explanation:

  • STRING – Combines FIRST-NAME and LAST-NAME into FULL-NAME.

  • UNSTRING – Breaks ADDRESS into STREET and CITY using commas as delimiters.

  • INSPECT –

    • TALLYING counts occurrences of a character.

    • REPLACING substitutes one character for another.

These operations allow COBOL programs to process and transform textual data efficiently — essential for generating reports, cleaning data, or preparing structured outputs.

3. Real-World Applications and Best Practices

Practical Scenarios:

  • 🧾 Report Generation: Format customer names or product details neatly.

  • 📧 Data Validation: Verify email or phone number patterns.

  • 🏦 Banking Systems: Clean and normalize text data before transactions.

  • 📦 Inventory Systems: Combine product codes and categories for identifiers.

Best Practices:

  • Always use DELIMITED BY carefully to avoid truncation.

  • Use INSPECT for counting, replacing, or verifying text integrity.

  • Allocate enough space (PIC X(n)) in receiving fields to prevent overflow.

  • When using UNSTRING, define the target fields clearly to match expected delimiters.

With these techniques, COBOL becomes a powerful tool not just for number crunching but also for structured text processing.

🧠 Key Takeaways

  • STRING joins multiple text fields into one.

  • UNSTRING splits a text field into multiple parts.

  • INSPECT analyzes or modifies characters in strings.

  • COBOL’s string verbs simplify data cleaning and report formatting.

  • Proper text handling enhances readability and accuracy in business outputs.

💻 Practice Task

  1. Create a program CUSTFORMAT.cbl that:

    • Accepts Customer Name, City, and Country.

    • Combines them into a single formatted string:
      "Customer: [Name], Location: [City] - [Country]"

    • Then splits it back using UNSTRING and displays each component.

  2. Use INSPECT to count how many times the letter “A” appears in the name.

  3. Bonus: Replace all lowercase letters in the city name with uppercase.



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