3 Programming with Eloquence

Programming Guidelines

Entering Programs

Be sure to check the following points before entering your first program:

50 Display_name:DISP "Name is, ";A$

NOTE: String constants and comments are limited to 255 characters. Comments cannot be positioned beyond column 255.

The following guidelines belong to the character oriented development environment, only:

Entering a Sample Program

Now you are ready to enter your first program. The next example shows some useful programming tips. The program is a simple guessing game which first computes an integer number between 0 and 9 and then gives the operator three chances to guess it. This example uses the character I/O (INPUT, DISP), so it cannot run on the NT platform.

10 REM
40 REM
50 REM  DATE WRITTEN: dd/mm/yy
60 REM  AUTHOR      : John SMITH
75 INTEGER Try,Guess,Number,You,Me
90    DISP  "~~"     ! Cursor home, clear display
100    PRINT "I'm thinking of a number between 0 and 9"
110    PRINT "You have three guesses"
120    Number = INT(RND*10)
130    FOR Try=1 TO 3
140        PRINT "Enter guess number, ";Try
150        INPUT "Now, ";Guess
160        IF Guess=Number THEN Win
170        IF Guess<Number THEN PRINT "Too Low"
180        IF Guess>Number THEN PRINT "Too High"
190    NEXT Try
200    !
210 Lose:  PRINT "Sorry, the number was: ";Number;"."
220           Me = Me+1
230           GOTO Tally
240 Win:   PRINT "That's right!"
250        You=You+1
260 Tally: PRINT SPA(30);"Game Score"
270        PRINT SPA(30);YOU      ME"
280        PRINT SPA(30);You;SPA(5);Me
290        WAIT 4000
300        INPUT "Do you want to play again? (YES/NO), ";Reply$
310 UNTIL Reply$="NO"
320 END
Here are some useful programming tips:

This programming tips are concerning line numbers and so they are useful for the character oriented development environment, only.

There is another way to insert lines, without concern for line numbers. This process involves using the list and store commands from the HP-UX prompt. List the program without line numbers (option -n) to an ASCII text file, insert your lines using an HP-UX editor or utility, and then store the program. When the store command converts the ASCII text file back to an Eloquence program file, it automatically renumbers the program in increments of one, starting with one. For more information see chapter , The LIST and list Commands.

Programming Aids

Program Annotations

The Eloquence language provides two ways to include non-executable text fields in program listings--the REM (remark) statement and the exclamation point (!) comment delimiter. All characters following either REM or ! are stored with the program but not executed. Any combination of text can follow each keyword, as shown in the next example. Notice that ! comment fields can be placed either on lines by themselves or after program statements. REM statements cannot.

10 ! You can say any **** thing you wish
20 ! in a REM statement
30 ! *********************************************
40 ! *                                           *
50 ! *      DOCUMENT YOUR PROGRAMS WELL!         *
60 ! *                                           *
70 ! *********************************************
80 PRINT "Enter Sales Code, ";Sales_Code
90 IF Sales_code < 1000 THEN Invalid_entry! Error_routine
100          ELSE
110             Enter_asale     !Code OK so user permitted entry
120                             !to Sales database
130          END IF

The Bit Bucket

When you wish to run programs that involve time-consuming output operations but do not want the output, you may assign program output to the Bit Bucket. This is an imaginary device where data is dumped and cannot be retrieved.

To assign output from the printer to the bit bucket, specify device address 9 in the appropriate printer assignment statement--PRINTER IS, SYSTEM PRINTER IS, or PRINT ALL IS. For example, to send all PRINT and PRINT USING output to the bit bucket, execute the following:

NOTE: Be sure to read page 252 before using these statements.

Creating programlines dynamically

With the COMMAND statement it is possible create programlines dynamically in the program.The COMMAND statement executes a statement contained within a string expression. The syntax is as follows:

Any executable, non-declarative statement (not DIM, COM, etc.) can be executed via COMMAND. For example, the following program uses a COMMAND statement to display a user selected variable:

10   INPUT Variable$
30   COMMAND "DISP "&Variable$
60   END
Note that the string expression can contain any combination of string characters within quotes, string variable names, substrings and string functions. String operations are described in page 73 .

One COMMAND statement can be executed by another COMMAND statement. However one COMMAND statement cannot call itself, nor can it call itself via intermediate COMMANDs. (The COMMAND statement is not recursive.) For example, the following sequence is permitted:

10   A$="COMMAND B$"
20   B$="DISP C$"
30   C$="OK"
50   END
However, the following sequence causes ERROR 156:

10   A$="COMMAND A$"
30   END

Execution of COMMAND Statements

1 Scan/parse Eloquence statement contained in a string expression and execute.

2 If the first character of a string expression is an exclamation mark (comment), a system command is executed. Stdout and stderr are redirected to SYPR. You can redirect them with output redirection.

3 If the first character of a string expression is an colon (:), a system command is executed. In this form it is possible to start a interactiv process, as an editor or a shell, except the 'ksh'.

It also supports the specification of a result string. If present, the output of a HP-UX command will be returned in the result string instead being output to the SYSTEM PRINTER.

Here is an example:

COMMAND "!uname -i",Serial$
DISP "Your serial number is ";Serial$

This example reads the serial number of the system and copies the output in the variable Serial$.

If the HP-UX or Windows command fails, you will receive error number 170, or a more detailed error code if you specified the return variable.

Here is an example:

COMMAND ":elm"

This example starts the 'elm' and after quiting this process the eloqcore refreshes the screen and continues.

Space Dependency

Each line entered is automatically checked by the Eloquence interpreter. This check not only shows syntax errors in the line, but also assists with line spacing. Two methods of assistance are provided.


This mode is the default. Power up or SCRATCH A will set the SPACE INDEPENDENT mode. The SPACE INDEPENDENT mode may be entered without a full reset by typing:




Store the following line using the default (SPACE INDEPENDENT) mode.

10 IF Hours_worked>40 THEN GOTO Overtime
You must key in each word correctly. All Eloquence keywords (for example, IF, THEN, and GOTO) must be in uppercase, while variables (Hours_worked), line labels (Overtime) and subroutine names must be in initial caps (meaning the first letter of each word is in uppercase, while the rest of the word is in lowercase). However, the spacing between words is not important.


10 IF Hours_worked> 40T HE NG OTOOv ertime
Both the above examples will enter the desired line correctly.


When the SPACE DEPENDENT mode is set, spaces between keywords and variables (or the lack of them) become significant. Keywords and variables must be separated from each other by at least one space. However, Eloquence variables, subprogram names, and labels can now be typed in any combination of uppercase and lowercase characters.

To set the SPACE DEPENDENT mode, execute:


Now, as each line is stored, the computer automatically sets all Eloquence keywords to uppercase and sets other words to initial caps. Text in quotes, in REM lines, and after ! comment fields is not affected.

To store the example line using the SPACE DEPENDENT mode, the case of each character is not important, but intraline spacing (between keywords, variables, labels, and subprogram names) is essential. Using the SPACE DEPENDENT mode type in and store either of these lines:

10 IF Hours_worked > 40 THEN GOTO OVERTIME

10 if hours_worked > 40 then goto overtime
Notice that each word is separated by at least one space. Leaving any spaces out in this example will result either in a syntax error or in an unexpected line. Note also that the underscore character, "_", cannot be altered. (A minus sign, "-", is not a lowercase underscore!)

In SPACE DEPENDENT mode, trying to store the following program line gives an appropriate error message.

The computer interprets this as an assignment statement and encounters an error when trying to assign the value 1 to the variable FORI.

Another problem is encountered in SD mode when entering the following:

This example would pass the Eloquence interpreter without error. Unfortunately, the interpreter would assign the value 50 to the short variable WHILEA, instead of performing the correct interpretation (that is, to begin a WHILE loop, governed by the test A=50).

Here are some rules to follow when entering programs in SPACE DEPENDENT mode:

Error Messages

There are three main types of errors.

Syntax Errors

Each line entered is automatically checked for syntax errors. The system will not accept an invalid Eloquence statement, and will help you by showing where the statement fails. However, a mistake in typing that accidentally forms another valid Eloquence statement cannot be detected.

How you will be informed about the error, depends on the development environment

Run-Time Errors

These errors only appear when a program is run. A run-time error will halt the program and display the line number where the error was found. Consider this fragment of a payroll program:

190 INPUT "Please Enter Number of Employees;",Emp_quantity
200 Emp_bonus = Total_bonus/Emp_quantity
210 PRINT Emp_bonus
If the operator enters an Emp_quantity of 0, an error 31 will occure. Error 31 indicates attempted division by 0. Note that this error can only be detected at run time, as a division by zero will only occur if an Emp_quantity of 0 is entered.

The line number displayed by a run-time error need not be the incorrect line. It merely shows the point at which the error was detected. These run-time errors can be handled (or "trapped") by the program by using the ON ERROR statement, as described in page 151 .

Internal Errors

If an irretrievable system condition occurs while Eloquence is running, it stops and issues an error message. The error message contains the reason Eloquence stopped, will be different displayed, on HP-UX and Windows NT. Please make a note of this information, and report it to Marxmeier Software AG. To continue working, restart Eloquence.

Eloquence Language Manual - 19 DEC 2002