COBOL COLS Function

The COLS function in COBOL provides advanced column positioning capabilities for multi-column layouts, table formatting, and complex screen designs. It extends beyond single column positioning to enable sophisticated data presentation and user interface design.

Overview and Purpose

The COLS function builds upon the basic COL functionality to provide more sophisticated column positioning capabilities. While COL positions output at a single column, COLS can handle multiple column specifications, ranges, and complex formatting scenarios. This makes it particularly valuable for creating tabular displays, multi-column reports, and structured screen layouts that require precise alignment across multiple data points.

In enterprise applications, data presentation often requires more than simple single-column positioning. Financial reports, customer listings, inventory displays, and administrative screens all benefit from the advanced formatting capabilities that COLS provides. Understanding how to effectively use COLS is essential for creating professional, readable, and maintainable user interfaces.

Basic Multi-Column Positioning

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DISPLAY "ID" AT COLS 1
DISPLAY "Name" AT COLS 10
DISPLAY "Amount" AT COLS 35

This example demonstrates basic multi-column header positioning for a tabular display. Each column header is positioned at a specific column using COLS, creating a structured layout where data can be aligned consistently. The ID column starts at position 1, the Name column at position 10, and the Amount column at position 35. This spacing provides adequate room for typical data while maintaining readability and professional appearance.

Dynamic Column Array Definition

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01  WS-COLUMN-POSITIONS.
    05  WS-COL-ID           PIC 99 VALUE 1.
    05  WS-COL-NAME         PIC 99 VALUE 10.
    05  WS-COL-AMOUNT       PIC 99 VALUE 35.
    05  WS-COL-STATUS       PIC 99 VALUE 50.

This working storage definition creates a structured approach to managing column positions. By defining column positions as named variables, you can easily modify the layout by changing the values in one location. This approach also makes the code more maintainable and allows for dynamic adjustment of column positions based on screen width, user preferences, or data content requirements. The named variables make the code self-documenting and easier to understand.

Table Row Display with COLS

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PERFORM VARYING WS-INDEX FROM 1 BY 1
    UNTIL WS-INDEX > WS-RECORD-COUNT
    DISPLAY CUSTOMER-ID(WS-INDEX) AT COLS WS-COL-ID
    DISPLAY CUSTOMER-NAME(WS-INDEX) AT COLS WS-COL-NAME
    DISPLAY CUSTOMER-AMOUNT(WS-INDEX) AT COLS WS-COL-AMOUNT
END-PERFORM

This loop demonstrates how to display tabular data using COLS positioning. Each iteration displays one row of customer data, with each field positioned at its designated column. The use of indexed data items and variable column positions creates a flexible table display that can accommodate varying amounts of data while maintaining consistent formatting. This pattern is fundamental for creating data grids and reports that present multiple records in an organized, readable format.

Conditional Column Positioning

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IF WS-DISPLAY-MODE = 'COMPACT'
    MOVE 5 TO WS-COL-SPACING
ELSE
    MOVE 15 TO WS-COL-SPACING
END-IF
 
COMPUTE WS-COL-NAME = WS-COL-ID + WS-COL-SPACING
COMPUTE WS-COL-AMOUNT = WS-COL-NAME + WS-COL-SPACING

This example shows how to implement responsive column positioning that adapts to different display modes. In compact mode, columns are spaced closer together to fit more information on screen, while normal mode uses wider spacing for better readability. The calculated column positions ensure consistent spacing regardless of the mode, and the approach can be extended to handle different screen sizes or user accessibility requirements.

Report Header with COLS Alignment

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DISPLAY "CUSTOMER REPORT" AT COLS 25
DISPLAY "Date: " AT COLS 1
DISPLAY WS-REPORT-DATE AT COLS 7
DISPLAY "Page: " AT COLS 60
DISPLAY WS-PAGE-NUMBER AT COLS 66

This report header example demonstrates how COLS can create professional document headers with multiple aligned elements. The main title is centered using column 25, while supporting information (date and page number) is positioned at the left and right edges respectively. This type of header formatting is essential for business reports that need to convey information clearly while maintaining a professional appearance suitable for management review or external distribution.

Form Field Alignment with COLS

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DISPLAY "Customer Information" AT COLS 20
DISPLAY "First Name:" AT COLS 5
DISPLAY "Last Name:" AT COLS 5
DISPLAY "Address:" AT COLS 5
DISPLAY "Phone:" AT COLS 5

This form layout uses COLS to create consistent field label alignment. All labels start at column 5, creating a clean left-aligned appearance, while the form title is centered at column 20. This type of consistent alignment is crucial for data entry forms where users need to quickly locate fields and understand the form structure. The predictable layout reduces data entry errors and improves user efficiency.

Multi-Level Data Display

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DISPLAY "Department: " AT COLS 1
DISPLAY DEPT-NAME AT COLS 15
DISPLAY "Manager: " AT COLS 5
DISPLAY MANAGER-NAME AT COLS 15
DISPLAY "Employee: " AT COLS 9
DISPLAY EMPLOYEE-NAME AT COLS 15

This example illustrates how COLS can create hierarchical data displays with different indentation levels. Department information starts at column 1, manager information is indented to column 5, and employee information is further indented to column 9. All data values align at column 15, creating a clean, organized appearance that clearly shows the relationship between different levels of information. This pattern is valuable for organizational charts, bill-of-materials displays, and other hierarchical data.

Error Message Positioning

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IF VALIDATION-ERROR
    DISPLAY "*** ERROR ***" AT COLS 30
    DISPLAY ERROR-MESSAGE AT COLS 25
    DISPLAY "Press any key to continue" AT COLS 20
END-IF

This error handling example shows how COLS can be used to create attention-grabbing error displays. The error indicator is centered at column 30, the error message is positioned at column 25, and the user instruction is at column 20. This creates a visually distinct error presentation that draws the user's attention while providing clear information about the problem and required action. Consistent error formatting helps users quickly recognize and respond to system messages.

Performance Optimization with COLS

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01  WS-SCREEN-BUFFER     PIC X(80).
01  WS-DISPLAY-METRICS.
    05  WS-COLS-OPERATIONS  PIC 9(6) VALUE ZERO.
    05  WS-BUFFER-WRITES    PIC 9(6) VALUE ZERO.

This performance monitoring structure tracks COLS operations and buffer usage. When dealing with large amounts of data or frequent screen updates, consider using screen buffering to build complete lines before displaying them. This can significantly improve performance compared to multiple individual COLS positioning operations. The metrics help identify performance bottlenecks and optimize screen handling in high-volume applications.

Tutorial: Creating Professional Reports

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01  WS-REPORT-COLUMNS.
    05  WS-COL-ITEM-CODE    PIC 99 VALUE 1.
    05  WS-COL-DESCRIPTION  PIC 99 VALUE 12.
    05  WS-COL-QUANTITY     PIC 99 VALUE 45.
    05  WS-COL-PRICE        PIC 99 VALUE 55.
    05  WS-COL-TOTAL        PIC 99 VALUE 70.

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DISPLAY "INVENTORY REPORT" AT COLS 30
DISPLAY "Item" AT COLS WS-COL-ITEM-CODE
DISPLAY "Description" AT COLS WS-COL-DESCRIPTION
DISPLAY "Qty" AT COLS WS-COL-QUANTITY
DISPLAY "Price" AT COLS WS-COL-PRICE
DISPLAY "Total" AT COLS WS-COL-TOTAL

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PERFORM VARYING WS-INDEX FROM 1 BY 1
    UNTIL WS-INDEX > WS-ITEM-COUNT
    DISPLAY ITEM-CODE(WS-INDEX) AT COLS WS-COL-ITEM-CODE
    DISPLAY ITEM-DESC(WS-INDEX) AT COLS WS-COL-DESCRIPTION
    DISPLAY ITEM-QTY(WS-INDEX) AT COLS WS-COL-QUANTITY
    DISPLAY ITEM-PRICE(WS-INDEX) AT COLS WS-COL-PRICE
    DISPLAY ITEM-TOTAL(WS-INDEX) AT COLS WS-COL-TOTAL
END-PERFORM

Practical Exercises

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01  WS-EMPLOYEE-COLS.
    05  WS-COL-EMP-ID       PIC 99 VALUE 1.
    05  WS-COL-EMP-NAME     PIC 99 VALUE 8.
    05  WS-COL-DEPARTMENT   PIC 99 VALUE 35.
    05  WS-COL-SALARY       PIC 99 VALUE 50.
 
DISPLAY "ID" AT COLS WS-COL-EMP-ID
DISPLAY "Employee Name" AT COLS WS-COL-EMP-NAME
DISPLAY "Department" AT COLS WS-COL-DEPARTMENT
DISPLAY "Salary" AT COLS WS-COL-SALARY

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COMPUTE WS-MENU-START = (80 - WS-MENU-WIDTH) / 2
DISPLAY "MAIN MENU" AT COLS WS-MENU-START
ADD 2 TO WS-MENU-START
PERFORM VARYING WS-INDEX FROM 1 BY 1
    UNTIL WS-INDEX > WS-MENU-ITEMS
    DISPLAY MENU-OPTION(WS-INDEX) AT COLS WS-MENU-START
END-PERFORM

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01  WS-FINANCIAL-COLS.
    05  WS-COL-ACCOUNT      PIC 99 VALUE 1.
    05  WS-COL-CURRENT      PIC 99 VALUE 40.
    05  WS-COL-PREVIOUS     PIC 99 VALUE 60.
 
DISPLAY "Account" AT COLS WS-COL-ACCOUNT
DISPLAY "Current Year" AT COLS WS-COL-CURRENT
DISPLAY "Previous Year" AT COLS WS-COL-PREVIOUS
DISPLAY ALL "-" AT COLS 1 SIZE 79

Advanced COLS Techniques

Responsive Layout Design

Implement responsive layouts that adapt to different screen widths by calculating column positions as percentages of available screen space. This ensures your applications work well on various terminal sizes and display configurations.

Template-Based Formatting

Create reusable formatting templates by defining standard column layouts for common screen types (lists, forms, reports). This promotes consistency across your application and reduces development time for new screens.

Accessibility Considerations

When designing column layouts, consider users who may need larger fonts or different display configurations. Ensure adequate spacing between columns and avoid overly compact layouts that may be difficult to read.