COBOL Tutorial

COBOL WRITE Statement

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WRITE Statement Overview

The WRITE statement is used to add new records to a file. It is one of the fundamental file processing verbs in COBOL, allowing programs to create and append data to files. The WRITE statement supports various options depending on the file organization and access mode.

Basic Syntax

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WRITE record-name
    [FROM data-name]
    [ADVANCING {identifier-1 | integer-1 | mnemonic-name} {LINE | LINES | PAGE}]
    [BEFORE | AFTER]
    [AT END-OF-PAGE imperative-statement-1]
    [NOT AT END-OF-PAGE imperative-statement-2]
    [END-WRITE]

The WRITE statement writes a record to a file. The record-name must be defined in the FILE SECTION and correspond to a file opened in OUTPUT, EXTEND, or I-O mode.

File Mode Requirements

File Mode	WRITE Allowed	Purpose
OUTPUT	Yes	Create new file, write records
EXTEND	Yes	Append records to existing file
I-O	Yes	Read and write operations
INPUT	No	Read-only operations

WRITE Statement Options

The WRITE statement supports several optional clauses that provide additional functionality for different file organizations and output requirements.

FROM Clause

The FROM clause copies data from a working storage field to the record before writing:

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* Basic FROM clause
WRITE CUSTOMER-RECORD FROM WS-CUSTOMER-DATA.
 
* FROM clause with literal
WRITE HEADER-RECORD FROM "CUSTOMER MASTER FILE".
 
* FROM clause with calculated data
COMPUTE WS-TOTAL = WS-AMOUNT + WS-TAX
WRITE TOTAL-RECORD FROM WS-TOTAL.

The FROM clause is useful when you want to write data from a different source than the record description, or when you need to perform calculations before writing.

ADVANCING Clause

The ADVANCING clause controls line spacing for LINE SEQUENTIAL files:

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* Single line advance (default)
WRITE REPORT-LINE ADVANCING 1 LINE.
 
* Double spacing
WRITE REPORT-LINE ADVANCING 2 LINES.
 
* Page break
WRITE REPORT-LINE ADVANCING PAGE.
 
* Variable spacing
WRITE REPORT-LINE ADVANCING WS-LINE-COUNT LINES.
 
* No advance
WRITE REPORT-LINE ADVANCING 0 LINES.

The ADVANCING clause is required for LINE SEQUENTIAL files and ignored for other file organizations. It controls how many lines to advance after writing the record.

BEFORE/AFTER ADVANCING

Controls when the line advance occurs relative to the WRITE operation:

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* AFTER ADVANCING (default) - advance after writing
WRITE REPORT-LINE AFTER ADVANCING 1 LINE.
 
* BEFORE ADVANCING - advance before writing
WRITE REPORT-LINE BEFORE ADVANCING 1 LINE.
 
* BEFORE ADVANCING PAGE - page break before writing
WRITE REPORT-LINE BEFORE ADVANCING PAGE.

BEFORE ADVANCING is useful when you want to write at a specific line position, while AFTER ADVANCING is the standard behavior for most applications.

AT END-OF-PAGE Clause

Handles page overflow conditions for LINE SEQUENTIAL files:

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WRITE REPORT-LINE
    AT END-OF-PAGE
        PERFORM PRINT-PAGE-HEADER
        MOVE 1 TO LINE-COUNTER
    NOT AT END-OF-PAGE
        ADD 1 TO LINE-COUNTER
END-WRITE.

The AT END-OF-PAGE clause allows you to handle page overflow conditions and perform special processing when a page break occurs.

File Organization Considerations

The behavior of the WRITE statement varies depending on the file organization. Understanding these differences is crucial for proper file handling.

Sequential Files

WRITE operations with sequential files are straightforward:

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* Sequential file WRITE
OPEN OUTPUT CUSTOMER-FILE
MOVE "JOHN DOE" TO CUSTOMER-NAME
MOVE "123 MAIN ST" TO CUSTOMER-ADDRESS
WRITE CUSTOMER-RECORD
CLOSE CUSTOMER-FILE.

Records are written in the order they are processed. No special considerations are needed for sequential files.

Indexed Files

Indexed files require key field values and support duplicate key handling:

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* Indexed file WRITE with error handling
OPEN OUTPUT CUSTOMER-FILE
MOVE "C001" TO CUSTOMER-ID
MOVE "JOHN DOE" TO CUSTOMER-NAME
WRITE CUSTOMER-RECORD
    INVALID KEY
        DISPLAY "Duplicate key: " CUSTOMER-ID
        PERFORM ERROR-HANDLING
    NOT INVALID KEY
        DISPLAY "Record written successfully"
END-WRITE
CLOSE CUSTOMER-FILE.

The INVALID KEY clause is essential for handling duplicate key errors in indexed files. The key field must be properly set before the WRITE operation.

Relative Files

Relative files require a relative record number for positioning:

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* Relative file WRITE
OPEN OUTPUT CUSTOMER-FILE
MOVE 1 TO CUSTOMER-ID
MOVE "JOHN DOE" TO CUSTOMER-NAME
WRITE CUSTOMER-RECORD
    INVALID KEY
        DISPLAY "Invalid relative record number: " CUSTOMER-ID
    NOT INVALID KEY
        DISPLAY "Record written at position: " CUSTOMER-ID
END-WRITE
CLOSE CUSTOMER-FILE.

The relative record number (key field) determines where the record is written. Gaps in the file are filled with empty records.

LINE SEQUENTIAL Files

LINE SEQUENTIAL files require the ADVANCING clause:

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* LINE SEQUENTIAL file WRITE
OPEN OUTPUT REPORT-FILE
MOVE "CUSTOMER REPORT" TO REPORT-LINE
WRITE REPORT-LINE ADVANCING 2 LINES
MOVE "================" TO REPORT-LINE
WRITE REPORT-LINE ADVANCING 1 LINE
CLOSE REPORT-FILE.

The ADVANCING clause is required for LINE SEQUENTIAL files to control line spacing. This is commonly used for report generation.

Error Handling and File Status

Proper error handling is essential when using WRITE statements. Understanding file status codes helps diagnose and handle errors effectively.

Common File Status Codes

Status Code	Meaning	Action Required
00	Successful operation	Continue processing
22	Duplicate key (indexed files)	Handle duplicate key logic
23	No record found	Check record existence
30	Permanent error	Check file permissions, disk space
34	Boundary violation	Check record size limits
35	File not found	Check file existence
37	File not open	Ensure file is opened

Error Handling Example

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IDENTIFICATION DIVISION.
PROGRAM-ID. WRITE-ERROR-HANDLING.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT CUSTOMER-FILE ASSIGN TO "CUSTOMER.DAT"
        ORGANIZATION IS INDEXED
        ACCESS MODE IS SEQUENTIAL
        RECORD KEY IS CUSTOMER-ID
        FILE STATUS IS CUSTOMER-STATUS.
 
DATA DIVISION.
FILE SECTION.
FD  CUSTOMER-FILE
    LABEL RECORDS ARE STANDARD
    RECORD CONTAINS 80 CHARACTERS.
01  CUSTOMER-RECORD.
    05  CUSTOMER-ID       PIC X(5).
    05  CUSTOMER-NAME     PIC X(30).
    05  CUSTOMER-ADDRESS  PIC X(45).
 
WORKING-STORAGE SECTION.
01  CUSTOMER-STATUS       PIC XX.
01  ERROR-MESSAGE         PIC X(50).
 
PROCEDURE DIVISION.
MAIN-PROCESS.
    PERFORM INITIALIZATION
    PERFORM WRITE-RECORDS
    PERFORM FINALIZATION
    STOP RUN.
 
INITIALIZATION.
    OPEN OUTPUT CUSTOMER-FILE
    IF CUSTOMER-STATUS NOT = "00"
        DISPLAY "Error opening file: " CUSTOMER-STATUS
        STOP RUN
    END-IF.
 
WRITE-RECORDS.
    MOVE "C001" TO CUSTOMER-ID
    MOVE "JOHN DOE" TO CUSTOMER-NAME
    MOVE "123 MAIN STREET" TO CUSTOMER-ADDRESS
    
    WRITE CUSTOMER-RECORD
        INVALID KEY
            PERFORM HANDLE-INVALID-KEY
        NOT INVALID KEY
            DISPLAY "Record written successfully"
    END-WRITE
    
    * Check file status after WRITE
    IF CUSTOMER-STATUS NOT = "00"
        PERFORM HANDLE-WRITE-ERROR
    END-IF.
 
HANDLE-INVALID-KEY.
    EVALUATE CUSTOMER-STATUS
        WHEN "22"
            MOVE "Duplicate key detected" TO ERROR-MESSAGE
        WHEN "30"
            MOVE "Permanent error occurred" TO ERROR-MESSAGE
        WHEN "34"
            MOVE "Boundary violation" TO ERROR-MESSAGE
        WHEN OTHER
            MOVE "Unknown error occurred" TO ERROR-MESSAGE
    END-EVALUATE
    DISPLAY "Error: " ERROR-MESSAGE.
 
HANDLE-WRITE-ERROR.
    DISPLAY "Write error - Status: " CUSTOMER-STATUS
    PERFORM FINALIZATION
    STOP RUN.
 
FINALIZATION.
    CLOSE CUSTOMER-FILE.

This example demonstrates comprehensive error handling for WRITE operations, including INVALID KEY processing and file status checking.

Practical Examples

These practical examples demonstrate common WRITE statement usage patterns for different scenarios and file types.

Example 1: Creating a Customer Master File

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IDENTIFICATION DIVISION.
PROGRAM-ID. CREATE-CUSTOMER-FILE.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT CUSTOMER-FILE ASSIGN TO "CUSTOMER.DAT"
        ORGANIZATION IS INDEXED
        ACCESS MODE IS SEQUENTIAL
        RECORD KEY IS CUSTOMER-ID
        FILE STATUS IS CUSTOMER-STATUS.
 
DATA DIVISION.
FILE SECTION.
FD  CUSTOMER-FILE
    LABEL RECORDS ARE STANDARD
    RECORD CONTAINS 100 CHARACTERS.
01  CUSTOMER-RECORD.
    05  CUSTOMER-ID       PIC X(5).
    05  CUSTOMER-NAME     PIC X(30).
    05  CUSTOMER-ADDRESS  PIC X(50).
    05  CUSTOMER-PHONE    PIC X(15).
 
WORKING-STORAGE SECTION.
01  CUSTOMER-STATUS       PIC XX.
01  RECORD-COUNT          PIC 9(5) VALUE 0.
 
PROCEDURE DIVISION.
MAIN-PROCESS.
    PERFORM INITIALIZATION
    PERFORM CREATE-CUSTOMERS
    PERFORM FINALIZATION
    STOP RUN.
 
INITIALIZATION.
    OPEN OUTPUT CUSTOMER-FILE
    IF CUSTOMER-STATUS NOT = "00"
        DISPLAY "Error opening file: " CUSTOMER-STATUS
        STOP RUN
    END-IF.
 
CREATE-CUSTOMERS.
    * Customer 1
    MOVE "C001" TO CUSTOMER-ID
    MOVE "JOHN DOE" TO CUSTOMER-NAME
    MOVE "123 MAIN STREET, ANYTOWN, USA" TO CUSTOMER-ADDRESS
    MOVE "(555) 123-4567" TO CUSTOMER-PHONE
    WRITE CUSTOMER-RECORD
    ADD 1 TO RECORD-COUNT
    
    * Customer 2
    MOVE "C002" TO CUSTOMER-ID
    MOVE "JANE SMITH" TO CUSTOMER-NAME
    MOVE "456 OAK AVENUE, SOMETOWN, USA" TO CUSTOMER-ADDRESS
    MOVE "(555) 987-6543" TO CUSTOMER-PHONE
    WRITE CUSTOMER-RECORD
    ADD 1 TO RECORD-COUNT
    
    * Customer 3
    MOVE "C003" TO CUSTOMER-ID
    MOVE "BOB JOHNSON" TO CUSTOMER-NAME
    MOVE "789 PINE ROAD, OTHERTOWN, USA" TO CUSTOMER-ADDRESS
    MOVE "(555) 456-7890" TO CUSTOMER-PHONE
    WRITE CUSTOMER-RECORD
    ADD 1 TO RECORD-COUNT.
 
FINALIZATION.
    CLOSE CUSTOMER-FILE
    DISPLAY "Created " RECORD-COUNT " customer records".

This example creates an indexed customer master file with three sample records.

Example 2: Report Generation with LINE SEQUENTIAL

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IDENTIFICATION DIVISION.
PROGRAM-ID. GENERATE-REPORT.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT REPORT-FILE ASSIGN TO "SALES-REPORT.TXT"
        ORGANIZATION IS LINE SEQUENTIAL
        FILE STATUS IS REPORT-STATUS.
 
DATA DIVISION.
FILE SECTION.
FD  REPORT-FILE
    LABEL RECORDS ARE OMITTED
    RECORD CONTAINS 80 CHARACTERS.
01  REPORT-LINE          PIC X(80).
 
WORKING-STORAGE SECTION.
01  REPORT-STATUS        PIC XX.
01  LINE-COUNTER         PIC 9(3) VALUE 0.
01  PAGE-COUNTER         PIC 9(3) VALUE 1.
 
PROCEDURE DIVISION.
MAIN-PROCESS.
    PERFORM INITIALIZATION
    PERFORM WRITE-REPORT-HEADER
    PERFORM WRITE-REPORT-BODY
    PERFORM WRITE-REPORT-FOOTER
    PERFORM FINALIZATION
    STOP RUN.
 
INITIALIZATION.
    OPEN OUTPUT REPORT-FILE.
 
WRITE-REPORT-HEADER.
    MOVE "SALES REPORT" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 2 LINES
    MOVE "=============" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 1 LINE
    MOVE "DATE: 12/31/2023" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 2 LINES.
 
WRITE-REPORT-BODY.
    MOVE "CUSTOMER    SALES AMOUNT    DATE" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 1 LINE
    MOVE "--------    ------------    ----" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 1 LINE
    
    MOVE "JOHN DOE    $1,250.00       12/15/2023" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 1 LINE
    MOVE "JANE SMITH  $2,100.00       12/20/2023" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 1 LINE
    MOVE "BOB JOHNSON $950.00         12/25/2023" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 1 LINE.
 
WRITE-REPORT-FOOTER.
    MOVE "--------    ------------    ----" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 1 LINE
    MOVE "TOTAL       $4,300.00" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 2 LINES
    MOVE "END OF REPORT" TO REPORT-LINE
    WRITE REPORT-LINE ADVANCING 1 LINE.
 
FINALIZATION.
    CLOSE REPORT-FILE.

This example demonstrates report generation using LINE SEQUENTIAL files with proper line spacing and formatting.

Example 3: Appending to Sequential File

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IDENTIFICATION DIVISION.
PROGRAM-ID. APPEND-TRANSACTIONS.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT TRANSACTION-FILE ASSIGN TO "TRANSACTIONS.DAT"
        ORGANIZATION IS SEQUENTIAL
        ACCESS MODE IS SEQUENTIAL
        FILE STATUS IS TRANSACTION-STATUS.
 
DATA DIVISION.
FILE SECTION.
FD  TRANSACTION-FILE
    LABEL RECORDS ARE STANDARD
    RECORD CONTAINS 50 CHARACTERS.
01  TRANSACTION-RECORD.
    05  TRANSACTION-ID    PIC X(10).
    05  TRANSACTION-DATE  PIC 9(8).
    05  TRANSACTION-AMT   PIC 9(7)V99.
    05  TRANSACTION-TYPE  PIC X.
    05  FILLER            PIC X(23).
 
WORKING-STORAGE SECTION.
01  TRANSACTION-STATUS   PIC XX.
01  APPEND-COUNT         PIC 9(3) VALUE 0.
 
PROCEDURE DIVISION.
MAIN-PROCESS.
    PERFORM INITIALIZATION
    PERFORM APPEND-TRANSACTIONS
    PERFORM FINALIZATION
    STOP RUN.
 
INITIALIZATION.
    OPEN EXTEND TRANSACTION-FILE
    IF TRANSACTION-STATUS NOT = "00"
        DISPLAY "Error opening file: " TRANSACTION-STATUS
        STOP RUN
    END-IF.
 
APPEND-TRANSACTIONS.
    * Append transaction 1
    MOVE "TXN001" TO TRANSACTION-ID
    MOVE 20231231 TO TRANSACTION-DATE
    MOVE 1250.50 TO TRANSACTION-AMT
    MOVE "S" TO TRANSACTION-TYPE
    WRITE TRANSACTION-RECORD
    ADD 1 TO APPEND-COUNT
    
    * Append transaction 2
    MOVE "TXN002" TO TRANSACTION-ID
    MOVE 20231231 TO TRANSACTION-DATE
    MOVE 750.25 TO TRANSACTION-AMT
    MOVE "P" TO TRANSACTION-TYPE
    WRITE TRANSACTION-RECORD
    ADD 1 TO APPEND-COUNT.
 
FINALIZATION.
    CLOSE TRANSACTION-FILE
    DISPLAY "Appended " APPEND-COUNT " transactions".

This example demonstrates appending records to an existing sequential file using the EXTEND mode.

Best Practices and Tips

Following these best practices ensures reliable and efficient WRITE operations in COBOL programs.

General Best Practices

Always check file status after WRITE operations to detect errors
Use appropriate file modes - OUTPUT for new files, EXTEND for appending, I-O for read/write
Handle INVALID KEY conditions for indexed and relative files
Validate data before writing to ensure data integrity
Use meaningful record names that clearly identify the data being written
Close files properly to ensure all data is written to disk

Performance Considerations

Batch WRITE operations when possible to reduce I/O overhead
Use appropriate blocking factors for sequential files
Minimize file opens/closes by processing multiple records per file session
Consider buffering for high-volume WRITE operations
Avoid unnecessary FROM clauses when the record description is sufficient

Error Handling Guidelines

Always include error handling for production programs
Log errors appropriately for debugging and monitoring
Provide meaningful error messages that help identify the problem
Handle file status codes systematically using EVALUATE statements
Consider recovery strategies for different types of errors
Test error conditions during development and testing

Common Pitfalls to Avoid

Writing to files opened in INPUT mode - this will cause errors
Forgetting the ADVANCING clause for LINE SEQUENTIAL files
Not setting key fields before writing to indexed files
Ignoring file status codes after WRITE operations
Writing records larger than defined in the record description
Not closing files after writing operations
Using wrong file organization for the intended purpose

Test Your Knowledge

1. What is the basic syntax of the WRITE statement in COBOL?

WRITE record-name FROM data-name
WRITE record-name
WRITE file-name
WRITE data-name TO record-name

2. When is the ADVANCING clause required in a WRITE statement?

Always required for all files
Only for LINE SEQUENTIAL files
Only for SEQUENTIAL files
Never required

3. What does the FROM clause do in a WRITE statement?

Specifies the source file
Copies data from a working storage field to the record before writing
Specifies the destination file
Controls file positioning

4. Which file organization requires a prior READ before using WRITE?

SEQUENTIAL
INDEXED
RELATIVE
All of the above

5. What is the purpose of the INVALID KEY clause in a WRITE statement?

To handle file open errors
To handle duplicate key errors in indexed files
To handle end-of-file conditions
To handle syntax errors

COBOL Tutorial

COBOL WRITE Statement

WRITE Statement Overview

Basic Syntax

File Mode Requirements

WRITE Statement Options

FROM Clause

ADVANCING Clause

BEFORE/AFTER ADVANCING

AT END-OF-PAGE Clause

File Organization Considerations

Sequential Files

Indexed Files

Relative Files

LINE SEQUENTIAL Files

Error Handling and File Status

Common File Status Codes

Error Handling Example

Practical Examples

Example 1: Creating a Customer Master File

Example 2: Report Generation with LINE SEQUENTIAL

Example 3: Appending to Sequential File

Best Practices and Tips

General Best Practices

Performance Considerations

Error Handling Guidelines

Common Pitfalls to Avoid

Test Your Knowledge

Frequently Asked Questions

Related Concepts

File Processing

File Organization Types

Sequential File Operations

Indexed File Operations

File Status and Error Handling

Related Pages

COBOL Tutorial

COBOL WRITE Statement

WRITE Statement Overview

Basic Syntax

File Mode Requirements

WRITE Statement Options

FROM Clause

ADVANCING Clause

BEFORE/AFTER ADVANCING

AT END-OF-PAGE Clause

File Organization Considerations

Sequential Files

Indexed Files

Relative Files

LINE SEQUENTIAL Files

Error Handling and File Status

Common File Status Codes

Error Handling Example

Practical Examples

Example 1: Creating a Customer Master File

Example 2: Report Generation with LINE SEQUENTIAL

Example 3: Appending to Sequential File

Best Practices and Tips

General Best Practices

Performance Considerations

Error Handling Guidelines

Common Pitfalls to Avoid

Test Your Knowledge

Frequently Asked Questions

What is the difference between WRITE and REWRITE in COBOL?

When should I use the ADVANCING clause in WRITE statements?

How do I handle errors when using the WRITE statement?

Can I use WRITE with files opened in INPUT mode?

What is the purpose of the BEFORE/AFTER ADVANCING clause?

Related Concepts

File Processing

File Organization Types

Sequential File Operations

Indexed File Operations

File Status and Error Handling

Related Pages