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COBOL Tutorial

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COBOL String Handling

String handling in COBOL refers to operations for manipulating character strings (alphanumeric data). COBOL provides powerful string manipulation capabilities through STRING (concatenation), UNSTRING (parsing), INSPECT (replacement and counting), and intrinsic functions. Understanding string handling is essential for data transformation, formatting, parsing, and text processing in COBOL programs.

This guide covers STRING for concatenating strings, UNSTRING for parsing strings, INSPECT for character operations, string functions, and best practices for effective string handling in COBOL.

STRING Statement

STRING concatenates multiple strings into a target field:

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       WORKING-STORAGE SECTION.
       01  FIRST-NAME         PIC X(20) VALUE 'JOHN'.
       01  LAST-NAME          PIC X(20) VALUE 'SMITH'.
       01  FULL-NAME          PIC X(50).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           STRING FIRST-NAME DELIMITED BY SIZE
                  " " DELIMITED BY SIZE
                  LAST-NAME DELIMITED BY SIZE
                  INTO FULL-NAME
           END-STRING
           
           DISPLAY "Full name: " FULL-NAME
           *> Displays: JOHN SMITH
           
           STOP RUN.

UNSTRING Statement

UNSTRING parses a source string into multiple target fields:

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       WORKING-STORAGE SECTION.
       01  INPUT-LINE         PIC X(50) VALUE 'JOHN,SMITH,12345'.
       01  FIRST-NAME         PIC X(20).
       01  LAST-NAME          PIC X(20).
       01  ID-NUMBER          PIC X(10).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           UNSTRING INPUT-LINE
               DELIMITED BY ","
               INTO FIRST-NAME
                    LAST-NAME
                    ID-NUMBER
           END-UNSTRING
           
           DISPLAY "First: " FIRST-NAME
           DISPLAY "Last: " LAST-NAME
           DISPLAY "ID: " ID-NUMBER
           
           STOP RUN.

INSPECT Statement

INSPECT performs character replacement and counting:

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       WORKING-STORAGE SECTION.
       01  TEXT-LINE          PIC X(50) VALUE 'Hello, World!'.
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           *> Replace commas with spaces
           INSPECT TEXT-LINE REPLACING ALL "," BY " "
           DISPLAY "After replace: " TEXT-LINE
           *> Displays: Hello  World!
           
           STOP RUN.

String Functions

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       WORKING-STORAGE SECTION.
       01  TEXT               PIC X(30) VALUE '  Hello World  '.
       01  TEXT-LENGTH         PIC 9(3).
       01  TEXT-UPPER          PIC X(30).
       01  TEXT-TRIMMED        PIC X(30).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           *> Get length
           COMPUTE TEXT-LENGTH = FUNCTION LENGTH(TEXT)
           
           *> Convert to uppercase
           MOVE FUNCTION UPPER-CASE(TEXT) TO TEXT-UPPER
           
           *> Trim spaces
           MOVE FUNCTION TRIM(TEXT) TO TEXT-TRIMMED
           
           DISPLAY "Length: " TEXT-LENGTH
           DISPLAY "Upper: " TEXT-UPPER
           DISPLAY "Trimmed: " TEXT-TRIMMED
           
           STOP RUN.

Complete String Handling Example

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       IDENTIFICATION DIVISION.
       PROGRAM-ID. STRING-HANDLING-EXAMPLE.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  CUSTOMER-ID         PIC 9(8) VALUE 12345678.
       01  CUSTOMER-NAME        PIC X(30) VALUE 'JOHN SMITH'.
       01  BALANCE              PIC S9(8)V99 VALUE 1234.56.
       01  FORMATTED-MESSAGE    PIC X(100).
       01  INPUT-CSV            PIC X(100) VALUE '12345,JOHN,SMITH,1000.00'.
       01  PARSED-FIELDS.
           05  PARSED-ID        PIC X(10).
           05  PARSED-FIRST     PIC X(20).
           05  PARSED-LAST      PIC X(20).
           05  PARSED-AMOUNT    PIC X(10).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           DISPLAY "=== String Handling Examples ==="
           
           *> STRING example - build formatted message
           STRING "Customer ID: " DELIMITED BY SIZE
                  CUSTOMER-ID DELIMITED BY SIZE
                  " | Name: " DELIMITED BY SIZE
                  CUSTOMER-NAME DELIMITED BY SIZE
                  " | Balance: $" DELIMITED BY SIZE
                  BALANCE DELIMITED BY SIZE
                  INTO FORMATTED-MESSAGE
           END-STRING
           DISPLAY "Formatted: " FORMATTED-MESSAGE
           
           *> UNSTRING example - parse CSV
           UNSTRING INPUT-CSV
               DELIMITED BY ","
               INTO PARSED-ID
                    PARSED-FIRST
                    PARSED-LAST
                    PARSED-AMOUNT
           END-UNSTRING
           DISPLAY "Parsed ID: " PARSED-ID
           DISPLAY "Parsed First: " PARSED-FIRST
           DISPLAY "Parsed Last: " PARSED-LAST
           DISPLAY "Parsed Amount: " PARSED-AMOUNT
           
           *> INSPECT example - clean data
           INSPECT FORMATTED-MESSAGE REPLACING ALL " " BY "-"
           DISPLAY "After INSPECT: " FORMATTED-MESSAGE
           
           STOP RUN.

Best Practices

  • Use STRING for concatenation: Building formatted strings
  • Use UNSTRING for parsing: Splitting delimited data
  • Handle OVERFLOW: Check for string overflow conditions
  • Use POINTER: For positioned string operations
  • Validate lengths: Ensure target fields are large enough
  • Use INSPECT: For character replacement and counting
  • Use functions: Leverage intrinsic functions when appropriate

Test Your Knowledge

1. What does STRING do?

  • Splits strings
  • Concatenates (combines) multiple strings
  • Replaces characters
  • Counts characters

2. What does UNSTRING do?

  • Combines strings
  • Parses (splits) a string into multiple fields
  • Replaces characters
  • Formats numbers

3. What is INSPECT used for?

  • String concatenation
  • Character replacement and counting
  • String parsing
  • Number formatting

4. What does DELIMITED BY SIZE mean?

  • Include only the delimiter
  • Include the entire source string
  • Exclude the source
  • Include up to the delimiter

Related Concepts

Related Concepts

Data Types

Understanding alphanumeric data types

Data Manipulation

Manipulating and transforming data

Output Formatting

Formatting output with strings

Related Pages