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COBOL Cheatsheet

A quick reference guide to COBOL syntax, data types, control structures, and other essential elements.

COBOL Fundamentals

Program Structure

COBOL programs are divided into four divisions:

  1. IDENTIFICATION DIVISION: Identifies the program.
  2. ENVIRONMENT DIVISION: Describes the computer environment.
  3. DATA DIVISION: Defines the data used by the program.
  4. PROCEDURE DIVISION: Contains the program logic.

Example:

IDENTIFICATION DIVISION.
PROGRAM-ID.  SAMPLE-PROGRAM.
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SOURCE-COMPUTER.  IBM-370.
OBJECT-COMPUTER. IBM-370.
DATA DIVISION.
FILE SECTION.
WORKING-STORAGE SECTION.
PROCEDURE DIVISION.
   DISPLAY 'Hello, World'.
   STOP RUN.

Data Types

PIC X(n)

Alphanumeric data, n is the length.

PIC 9(n)

Numeric data, n is the number of digits.

PIC A(n)

Alphabetic data, n is the length.

PIC S9(n)

Signed numeric data, n is the number of digits.

PIC V

Implied decimal point.

Data Definition

Data is defined in the DATA DIVISION within the WORKING-STORAGE SECTION or FILE SECTION.

Example:

WORKING-STORAGE SECTION.
01  CUSTOMER-NAME PIC X(30).
01  CUSTOMER-AGE  PIC 9(02).
01  PI  PIC 9V99 VALUE 3.14.

Control Structures

IF Statement

Conditional execution based on a condition.

Syntax:

IF condition THEN
    statements
ELSE
    statements
END-IF.

Example:

IF CUSTOMER-AGE > 18 THEN
    DISPLAY 'Customer is an adult'
ELSE
    DISPLAY 'Customer is a minor'
END-IF.

EVALUATE Statement

Multi-way branch based on the value of a variable.

Syntax:

EVALUATE variable
    WHEN value1
        statements
    WHEN value2
        statements
    WHEN OTHER
        statements
END-EVALUATE.

Example:

EVALUATE CUSTOMER-CODE
    WHEN 1
        DISPLAY 'Premium Customer'
    WHEN 2
        DISPLAY 'Gold Customer'
    WHEN OTHER
        DISPLAY 'Standard Customer'
END-EVALUATE.

PERFORM Statement

PERFORM paragraph-name.

Executes a paragraph once.

PERFORM paragraph-name n TIMES.

Executes a paragraph n times.

PERFORM paragraph-name UNTIL condition.

Executes a paragraph until the condition is true.

PERFORM paragraph-name VARYING identifier FROM initial BY increment UNTIL condition.

Executes a paragraph, varying a counter from an initial value by an increment until a condition is met.

File Handling

File Section

Describes the structure and organization of data files.

Example:

FILE SECTION.
FD  CUSTOMER-FILE.
01  CUSTOMER-RECORD.
    05  CUSTOMER-ID   PIC 9(5).
    05  CUSTOMER-NAME PIC X(30).

File Operations

OPEN INPUT file-name.

Opens a file for reading.

OPEN OUTPUT file-name.

Opens a file for writing.

READ file-name INTO record-name AT END statements.

Reads a record from a file.

WRITE record-name FROM variable-name.

Writes a record to a file.

CLOSE file-name.

Closes a file.

Example: Reading a File 

PROCEDURE DIVISION.
    OPEN INPUT CUSTOMER-FILE.
    PERFORM UNTIL END-OF-FILE
        READ CUSTOMER-FILE INTO CUSTOMER-RECORD
            AT END
                MOVE 'Y' TO END-OF-FILE
            NOT AT END
                DISPLAY CUSTOMER-ID, CUSTOMER-NAME
        END-READ.
    END-PERFORM.
    CLOSE CUSTOMER-FILE.
    STOP RUN.

String Handling & Tables

String Manipulation

STRING ... DELIMITED BY ... INTO ...

Concatenates strings into a single string.

UNSTRING ... DELIMITED BY ... INTO ...

Splits a string into multiple strings based on delimiters.

INSPECT ... REPLACING ...

Replaces characters or substrings within a string.

Tables (Arrays)

Tables are defined using the OCCURS clause.

Example:

01  EMPLOYEE-TABLE.
    05  EMPLOYEE-RECORD OCCURS 10 TIMES.
        10  EMPLOYEE-ID   PIC 9(5).
        10  EMPLOYEE-NAME PIC X(30).

Accessing table elements:

DISPLAY EMPLOYEE-NAME(5).

Example of Table Processing:

PROCEDURE DIVISION.
    PERFORM VARYING I FROM 1 BY 1 UNTIL I > 10
        DISPLAY EMPLOYEE-NAME(I)
    END-PERFORM.

Search Statement

The SEARCH statement is used to find a specific element in a table.

Example:

SEARCH EMPLOYEE-TABLE
    AT END
        DISPLAY 'Employee not found'
    WHEN EMPLOYEE-ID(I) = SEARCH-ID
        DISPLAY EMPLOYEE-NAME(I)
END-SEARCH.
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