This document contains the following exercises:
You will now write your first short program which displays "Hello World!". It will be stored in the library you have created previously.
To create a new program
Make sure that you have logged on to the library named
TUTORIAL.
At the bottom of the Development Functions menu, enter the following information and press ENTER:
Code .. C Type .. P
Name .. HELLO___________________________
Command ===>
Enter-PF1---PF2---PF3---PF4---PF5---PF6---PF7---PF8---PF9---PF10--PF11--PF12---
Help Menu Exit Canc |
"C" stands for the function Create Object, "P" stands for the object type program, and "HELLO" is the name of the program to be created.
Tip:
When you enter the function code C, you can
also enter an asterisk (*) in the Type field. When you
press ENTER, a list of all object types and the letters that
correspond to these object types is shown.
The program editor appears. It is currently empty.
Enter the following code in the program editor:
* The "Hello world!" example in Natural. * DISPLAY "Hello world!" END /* End of program
Comment lines start with an asterisk (*) followed by at least one blank or a second asterisk. When you forget to enter the blank or second asterisk, Natural assumes that you have specified a system variable; this will result in an error.
If you want to insert empty lines in your program, you should define them as comment lines. This is helpful, if you want to access your program from different platforms (Windows, mainframe, UNIX or OpenVMS). With the mainframe version of Natural, for example, the default is that empty lines are automatically deleted when you press ENTER.
You can also insert comments at the end of a statement line. In this case, the comment starts with a slash followed by an asterisk (/*).
The text that is to be shown in the output is defined with the
DISPLAY statement. It is enclosed in quotation marks.
The END statement is used to mark the physical end of a
Natural program. Each program must end with END.
When you press ENTER, it may happen that all of your lower-case characters are translated to upper-case characters. This behavior is defined in the editor profile (which is explained later).
The system command RUN automatically invokes
the system command CHECK which checks the program
code for errors. If no error is found, the program is compiled on the fly and
then executed.
Notes:
CHECK is also available as a separate
command.
EXECUTE which uses the stowed version of your
program (stowing a program is explained later in this tutorial). In contrast to
this, the RUN command always uses your latest
modifications to the program.
To run a program
In the program editor's command line, enter one of the following:
RUN
R
System commands may be abbreviated.
R is the abbreviated form of
RUN.
Depending on the definitions in your environment, the command line is located either at the top or bottom of the screen.
> RUN > + Program HELLO Lib TUTORIAL |
When your code is syntactically correct, the output contains the text you have defined.
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Hello world!
Press ENTER to return to the program editor.
You will now create an error in your Hello World program and then run the program once more.
To correct an error
Delete the second quotation mark in the line containing the
DISPLAY statement.
Run the program once more as described above.
When the error is found, an error message is displayed.
NAT0305 Text string must begin and end on the same line.
> > + Program HELLO Lib TUTORIAL
All ....+....1....+....2....+....3....+....4....+....5....+....6....+....7..
0010 * The "Hello world!" example in Natural.
0020 *
E 0030 DISPLAY "HELLO WORLD!
0040 END /* End of program
0050
0060
0070
0080
0090
0100
0110
0120
0130
0140
0150
0160
0170
0180
0190
0200
....+....1....+....2....+....3....+....4....+....5....+... S 4 L 1 |
The statement line that contains the error is highlighted and marked with an "E".
Correct the error, that is: insert the missing quotation mark at the end of the line.
Run the program once more to find the next error.
In this case, no more errors are found and the output is shown.
Press ENTER to return to the program editor.
When you stow a program, it is compiled and both source code and a generated program are stored in the Natural system file.
Like the RUN command, the system command
STOW automatically invokes the
CHECK command. A program is only stowed when it is
syntactically correct.
Note:
If you want to save the changes to your program, even if the program
contains a syntactical error (for example, if you want to suspend your work
until the next day), you can use the system command
SAVE.
To stow a program
In the program editor's command line, enter the following:
STOW
The LIST command is useful to find out
whether only the source code or both source code and a generated program are
available for an object.
To display information about a program
In the program editor's command line, enter one of the following:
LIST DIR HELLO
L DIR HELLO
The following screen appears. The information provided with Cataloged on is only available when the object has been stowed.
13:15:45 ***** NATURAL LIST COMMAND ***** 2007-03-20
User SAG - List Directory - Library TUTORIAL
Directory of Program HELLO Saved on ... 2007-03-20 13:15:36
-------------------------------------------------------------------------------
Library .... TUTORIAL User-ID ...... SAG Mode ....... Structured
TP-System .. COMPLETE Terminal-ID .. DAEFTCA9
Op-System .. MVS/ESA Transaction .. NATvr
NAT-Ver .... v.r.s
Source size .......................... 100 Bytes
Directory of Program HELLO Cataloged on 2007-03-20 13:15:36
-------------------------------------------------------------------------------
Library .... TUTORIAL User-ID ...... SAG Mode ....... Structured
TP-System .. COMPLETE Terminal-ID .. DAEFTCA9
Op-System .. MVS/ESA Transaction .. NATvr
NAT-Ver .... v.r.s
Used GDA ...
Size of global data ... 0 Bytes Size in DATSIZE ...... 560 Bytes
Size in buffer pool ... 2620 Bytes
Size of OPT-Code ...... 0 Bytes
Initial OPT string ....
ENTER to continue |
Note:
In the above example, the notations
vr and v.r.s stand for
the current version number of Natural. See also the definition of
Version in the Glossary.
Press ENTER to return to the program editor.
The LIST command can also be used to display
a list of all Natural objects in the current library. This is helpful, for
example, if you decide at some point during this tutorial that you want to
delete one or more of your Natural objects in order to start again from the
very beginning.
To display a list of Natural objects
In the program editor's command line, enter one of the following:
LIST *
L *
The following screen appears. It lists the program you have just created.
13:34:27 ***** NATURAL LIST COMMAND ***** 2007-03-20
User SAG - LIST Objects in a Library - Library TUTORIAL
Cmd Name Type S/C SM Version User ID Date Time
--- *________ *__________ *__ * *______ *________ *__________ *________
__ HELLO Program S/C S v.r.s SAG 2007-03-20 13:15:36
1 Objects found
Top of List.
Command ===>
Enter-PF1---PF2---PF3---PF4---PF5---PF6---PF7---PF8---PF9---PF10--PF11--PF12---
Help Print Exit Sort -- - + ++ > Canc |
To find out which commands are available, enter a question mark (?) in the Cmd column next to your program.
The following window appears.
+-------- COMMANDS ---------+ ! ! ! ED Edit ! ! LI List ! ! LD List Dir ! ! PR Print ! ! LE List expanded ! ! RU Run ! ! ST Stow ! ! CA Catalog ! ! DE Delete ! ! RE Rename ! ! . End ! ! ! ! ! ! ! ! ! ! ! ! __ HELLO ! +---------------------------+ |
Do not apply any changes right now. Press PF3 to close the window without specifying any command.
Press PF3 once more to return to the program editor.
When working with the Natural program editor or data area editor, an editor profile can be defined per
user. This tutorial uses the default settings of the editor profile named
SYSTEM. Some important settings are mentioned below.
To check the editor profile options
In the program editor's command line, enter the following:
PROFILE
The following screen appears.
13:35:43 ***** NATURAL EDITORS ***** 2007-03-20
- Editor Profile -
Profile Name .. SYSTEM__
PF and PA Keys
PF1 ... HELP___________ PF2 ... _______________ PF3 ... EXIT___________
PF4 ... _______________ PF5 ... _______________ PF6 ... _______________
PF7 ... -______________ PF8 ... +______________ PF9 ... _______________
PF10 .. SC=____________ PF11 .. _______________ PF12 .. CANCEL_________
PF13 .. _______________ PF14 .. _______________ PF15 .. MENU___________
PF16 .. _______________ PF17 .. _______________ PF18 .. _______________
PF19 .. --_____________ PF20 .. ++_____________ PF21 .. _______________
PF22 .. _______________ PF23 .. _______________ PF24 .. _______________
PA1 ... _______________ PA2 ... SCAN___________ PA3 ... _______________
Automatic Functions
Auto Renumber .. Y Auto Save Numbers .. 0__ Source Save into .. EDITWORK
Additional Options .. N
Command ===>
Enter-PF1---PF2---PF3---PF4---PF5---PF6---PF7---PF8---PF9---PF10--PF11--PF12---
Help Exit AddOp Save Flip Del Canc |
When a user-specific editor profile does not exist, the default
profile SYSTEM is displayed. This default profile can be used to
create a user-specific profile. When a user-specific profile exists already, it
is displayed instead of the SYSTEM profile.
In the Additional Options field, enter "Y" and press ENTER.
Or:
Press PF4.
The following window appears.
+--------------------- ADDITIONAL OPTIONS ----------------------+ ! ! ! ! ! + Editor Defaults ......... N ! ! + General Defaults ........ N ! ! + Colour Definitions ...... N ! ! ! ! ! ! ! ! ! ! ! +---------------------------------------------------------------+ |
Enter "Y" in the fields Editor Defaults and General Defaults, and press ENTER.
The following window appears for the editor defaults.
+----------------------- EDITOR DEFAULTS -----------------------+ ! ! ! Escape Character for Line Command .. . ! ! Empty Line Suppression ............. Y ! ! Source Size Information ............ N ! ! Source Status Message .............. N ! ! Absolute Mode for SCAN/CHANGE ...... N ! ! Range Mode for SCAN/CHANGE ......... N ! ! Direction Indicator ................ + ! ! ! ! ! +---------------------------------------------------------------+ |
You can see the escape character that has been defined for line commands. This tutorial assumes that the default character, which is the a period (.), is used.
This tutorial also assumes that the option Empty Line Suppression is set to "Y". In this case, all blank lines in the program editor are automatically deleted when you press ENTER. They are not deleted when this option is set to "N".
For this tutorial, you should make sure that all options are set as shown above. Press ENTER to display the next window.
The following window appears.
+---------------------- GENERAL DEFAULTS -----------------------+ ! ! ! Editing in Lower Case .............. N ! ! Dynamic Conversion of Lower Case ... Y ! ! Position of Message Line ........... TOP ! ! Cursor Position in Command Line .... N ! ! Stay on Current Screen ............. N ! ! Prompt Window for Exit Function .... Y ! ! ISPF Editor as Program Editor ...... N ! ! Leave Editor with Unlock ........... N ! ! ! +---------------------------------------------------------------+ |
When the option Editing in Lower Case is set to "Y" and the option Dynamic Conversion of Lower Case is set to "N", any source code remains as you enter it. This feature, however, also depends on system-environment-specific settings which may force an uppercase translation of all of your input; this cannot be influenced by Natural.
If desired, change the above mentioned options for lowercase conversion and press ENTER. Press ENTER once more to return to the Additional Options window, and then press ENTER again to close this window.
When a user-specific profile has not yet been created, overwrite the
profile name SYSTEM with your user ID and press
ENTER.
When a user-specific profile exists already, proceed with the next step.
Press PF5 to save your changes in the database and then press PF3 to exit the editor profile.
Note:
Instead of pressing a PF key, you can also enter the corresponding
command in the command line. For example, in the above case, you can enter the
commands SAVE and
EXIT.
Or:
If you do not want to apply any changes, press PF3 to exit
the editor profile.
The exit function displays a window with different options. It even appears if you have just saved your changes.
+----------- EXIT Function -----------+ ! ! ! _ Save and Exit ! ! _ Exit without Saving ! ! _ Resume Function ! ! ! ! ! +-------------------------------------+ |
When you have saved your changes immediately before invoking the exit function, you can safely select the option Exit without Saving. Press ENTER to return to the program editor.
Caution:
If you have made further changes after pressing PF5
or issuing the SAVE command and now select the
option Exit without Saving, your latest changes are only
valid for the current session; they are not saved on the database.
Your program is shown again. Any new settings will now be used in the program editor (and also in the data area editor which is explained later).
You can now proceed with the next exercises: Database Access.