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COBOL Tutorial

COBOL SCROLL Clause - Quick Reference

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Overview

The SCROLL clause is used to control screen scrolling behavior in COBOL screen handling. It determines how content is displayed when it exceeds the available screen area.

Purpose and Usage

  • Screen scrolling - Control scrolling direction and behavior
  • Content display - Handle content that exceeds screen size
  • User interface - Improve user experience with large datasets
  • Display control - Manage screen content flow

Syntax

The SCROLL clause provides control over screen scrolling behavior.

Basic Syntax

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* Basic SCROLL clause syntax
SCREEN SECTION.
01  screen-name.
    05  field-name PIC X(n) 
        SCROLL [parameters].
 
* Example with scrolling
SCREEN SECTION.
01  SCROLLING-SCREEN.
    05  BLANK SCREEN.
    05  LINE 1 COLUMN 1 PIC X(80) SCROLL.
    05  LINE 2 COLUMN 1 PIC X(80) SCROLL.
    05  LINE 3 COLUMN 1 PIC X(80) SCROLL.
    * Additional scrolling lines...

SCROLL controls how content moves on the screen.

Practical Examples

Examples of using the SCROLL clause in different scenarios.

Scrolling List Display

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* Scrolling list with SCROLL clause
SCREEN SECTION.
01  LIST-SCREEN.
    05  BLANK SCREEN.
    05  LINE 1 COLUMN 1 VALUE "CUSTOMER LIST" REVERSE-VIDEO.
    05  LINE 3 COLUMN 1 PIC X(80) SCROLL.
    05  LINE 4 COLUMN 1 PIC X(80) SCROLL.
    05  LINE 5 COLUMN 1 PIC X(80) SCROLL.
    05  LINE 6 COLUMN 1 PIC X(80) SCROLL.
    05  LINE 7 COLUMN 1 PIC X(80) SCROLL.
    05  LINE 8 COLUMN 1 PIC X(80) SCROLL.
    05  LINE 9 COLUMN 1 PIC X(80) SCROLL.
    05  LINE 10 COLUMN 1 PIC X(80) SCROLL.
    05  LINE 20 COLUMN 1 VALUE "Press ENTER to continue" BLINK.

SCROLL enables smooth scrolling through long lists.

Best Practices

Understanding best practices ensures effective use of the SCROLL clause.

Best Practices

  • Use appropriately - Apply SCROLL only when needed
  • Test thoroughly - Verify scrolling behavior
  • Consider user experience - Ensure smooth scrolling
  • Handle large datasets - Use SCROLL for long content

Test Your Knowledge

1. What is the primary purpose of the SCROLL clause in COBOL?

  • To scroll text on the screen
  • To move data between files
  • To sort data in ascending order
  • To format text output

2. In which COBOL section is the SCROLL clause typically used?

  • SCREEN SECTION
  • DATA DIVISION
  • PROCEDURE DIVISION
  • ENVIRONMENT DIVISION

3. What does the SCROLL clause control?

  • File operations
  • Screen scrolling direction and behavior
  • Data validation
  • Memory allocation

4. Can SCROLL be used with all display operations?

  • Yes, with all displays
  • Only with specific screen types
  • Only with terminal displays
  • Only with printer output

5. What is the relationship between SCROLL and screen size?

  • No relationship
  • SCROLL affects how content fits on screen
  • SCROLL determines screen size
  • Screen size determines SCROLL behavior

Frequently Asked Questions

Related Concepts

SCREEN SECTION

Understanding the SCREEN SECTION in COBOL.

Display Formatting

Display formatting techniques in COBOL.

User Interface Design

Designing user interfaces in COBOL.

SCREEN ClauseSD Statement