Version 4.2.6 for Mainframes
 —  First Steps  —

Inline Subroutines

Natural distinguishes two types of subroutines: inline subroutines which are defined directly in the program and external subroutines which are stored as separate objects outside the program (this is explained later in this tutorial).

You will now add an inline subroutine to your program which moves an asterisk (*) to the new user-defined variable named #MARK. This subroutine will be invoked when an employee has 20 days of leave or more.

When you have completed the exercises below, your sample application will be structured as follows:

Application structure

This document contains the following exercises:


Defining the Inline Subroutine

You will now add the subroutine to your program.

Start of instruction setTo define the subroutine

  1. Insert the following below the user-defined variable #NAME-END:

    1 #MARK              (A1)

    This variable will be used by the subroutine. Therefore, it has to be defined first.

  2. To define the subroutine, insert the following before the END statement:

    DEFINE SUBROUTINE MARK-SPECIAL-EMPLOYEES
      MOVE '*' TO #MARK
    END-SUBROUTINE

    When performed, this subroutine moves an asterisk (*) to #MARK.

    Note:
    Instead of using the statement MOVE '*' TO #MARK it is also possible to use the following variant of the ASSIGN or COMPUTE statement: #MARK := '*'.

  3. Modify the DISPLAY statement as follows:

    DISPLAY NAME 3X DEPT 3X LEAVE-DUE 3X '>=20' #MARK

    This displays a new column in your output. Its heading is ">=20". The column will contain an asterisk (*) if the corresponding employee has 20 days of leave or more.

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Performing the Inline Subroutine

Now that you have defined the inline subroutine, you can specify the corresponding code for performing it.

Start of instruction setTo perform the inline subroutine

  1. Insert the following before the DISPLAY statement:

    IF LEAVE-DUE >= 20 THEN
      PERFORM MARK-SPECIAL-EMPLOYEES
    ELSE
      RESET #MARK
    END-IF

    When an employee is found who has 20 days of leave or more, the new subroutine named MARK-SPECIAL-EMPLOYEES is performed. When an employee has less than 20 days of leave, the content of #MARK is reset to blank.

    Your program should now look as follows:

    DEFINE DATA
    LOCAL
      1 #NAME-START        (A20)
      1 #NAME-END          (A20)
      1 #MARK              (A1)
      1 EMPLOYEES-VIEW VIEW OF EMPLOYEES
        2 FULL-NAME
          3 NAME (A20)
        2 DEPT (A6)
        2 LEAVE-DATA
          3 LEAVE-DUE (N2)
    END-DEFINE
    *
    RP1. REPEAT
    *
      INPUT USING MAP 'MAP01'
    *
      IF #NAME-START = '.' THEN
        ESCAPE BOTTOM (RP1.)
      END-IF
    *
      IF #NAME-END = ' ' THEN
        MOVE #NAME-START TO #NAME-END
      END-IF
    *
      RD1. READ EMPLOYEES-VIEW BY NAME
        STARTING FROM #NAME-START
        ENDING AT #NAME-END
    *    
        IF LEAVE-DUE >= 20 THEN
          PERFORM MARK-SPECIAL-EMPLOYEES
        ELSE
          RESET #MARK
        END-IF
    *
        DISPLAY NAME 3X DEPT 3X LEAVE-DUE 3X '>=20' #MARK
    *
      END-READ
    *
      IF *COUNTER (RD1.) = 0 THEN
        REINPUT 'No employees meet your criteria.'
      END-IF
    *
    END-REPEAT
    *
    DEFINE SUBROUTINE MARK-SPECIAL-EMPLOYEES
      MOVE '*' TO #MARK
    END-SUBROUTINE
    *
    END
  2. Run the program.

  3. In the resulting map, enter "JONES" and press ENTER.

    The list of employees should now contain the additional column.

  4. To return to the program editor, enter EDIT at the MORE prompt.

  5. Stow the program.

  6. Enter a dot (.) in the command line to return to the Development Functions menu.

You can now proceed with the next exercises: Processing Rules and Helproutines.

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