I am having a problem using a Common statement in a subroutine. I get an error - 'Attempt to use Common variables when COMMON not defined.'

I then used the code fragment at the bottom of page 54 in the R/BASIC manual in a test routine and I get the same reult! What am I missing?

Help please!

COMMON statements need to before the variables are used in the program. The called SUBROUTINE needs to have matching common statements after which the variables can be used.

Example:

progid=CALLINGPROG

---

COMMON A,B,C

A=variable A'

PRINT 'This is CALLINGPROG'

CALL EXTERNALSUB

PRINT A

*

progid=EXTERNALSUB

---

SUBROUTINE EXTERNALSUB

COMMON A,B,C

PRINT 'This is EXTERNALSUB'

PRINT A

A=has been changed'

RETURN

Warren,

Many thanks.

Simple, but not obvious!!!!!!!!!

Rick

Warren, or anyone else.

Not so simple!

Here is subroutine_1:

line 1 COMMON IC,LOG_NO

line 185 LOG_NO='

Here is subroutine_2, EXECUTED by subroutine_1 at line 200:

line 1 COMMON IC,LOG_NO

Both compile fine but when I run subroutine_2 it breaks at line 185 with Msg "Attempt to use COMMON variable when COMMON has not been defined"

What is wrong?

Rick

You must CALL the subroutine not EXECUTE it. EXECUTE loads a new TCL level and runs the program so it sets up a new memory space which is not aware of the memory that is being used by sub 1.

Your example would be better served as

Subroutine Sub1

Common IC, LogNo

LogNo=12

IC='

Call Sub2

Return

 

Subroutine Sub2

Common IC, LogNo

LogNo -= 10

Return

The Sprezzatura Group

World Leaders in all things RevSoft

The CALLed subroutine must be cataloged also (well, in 3.1x it doesn't HAVE to be as the RBasic runtime engine will as where the object code is, but that is an RPITA in production).

One could always use named commons, which allow more flexibility but eat up string/variable space in memory. There's no such thing as free lunch.

We don't know - there's this little soup kitchen at the corner of Grammercy and Lex that seems to do it. Do you know something we don't?

The Sprezzatura Group

World Leaders in all things RevSoft

Warren,

Both subroutines are cataloged! Not running on a run-time version. Any other thoughts?

What's an RPITA?

Rick

Hmmm, every soup kitchen I've been to I've had to pay dearly for the meal one way or another.

I guess you wonky Brits have higher standards of cleanliness or stronger stomachs than us Yanks.

In our country there's a famous folk song "Waltzing Matilda"

"Once a jolly swagman cramped by a billabong…."

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