OpenEuphoria

Re: Coming From QBasic

• Posted by Jason Gade <jaygade at yahoo.com> Jan 17, 2006
• 520 views

Lynn Kilroy wrote:
> 
> I see nothing wrong with passing an argument to a subroutine/procedure {to 
> me, these are really the same thing}, and allowing that subroutine to alter
> 
> it.  In QBasic, if I said:
> 
> >DECLARE SUB Inke (a AS STRING)
> >
> >SUB Inkey (a AS STRING)
> >a = INKEY$
> >END SUB
> 
> what I'm saying is Inkey requires the argument 'a,' which passes data to and
> 
> can also extract data from the subroutine.   If I included a local variable
> 
> in that subroutine:
> 
> >DECLARE SUB Inke (a AS STRING)
> >
> >SUB Inkey (a AS STRING)
> >
> >DIM Variable AS DOUBLE
> >
> >Variable = RND
> >
> >a = INKEY$
> >
> >END SUB
> 
> then Variable is only remembered by Inkey. but is never seen by the rest of
> 
> the program.  In this case, it is a useless excercise becuase nothing is 
> done with it.  As you say, local versus global.
> 
> Also, in both cases above, the line
> 
> >SUB Inkey (a AS STRING)
> 
> means you *MUST* pass it an argument.  That argument can be either a 
> variable pointer or a constant hard coded as an argument.  In the case of 
> Inkey, you could pass it arguments the following way, and they would all 
> work.
> 
> >DIM KeyPress AS STRING
> >
> >Inkey KeyPress
> 
> -Or-
> 
> >Inkey X$
> 
> -Or-
> 
> >Inkey " "
> 
> The first two are variables.  I never use the signed variables.  Poor form,
> 
> and rather tasteless to me, anymore, so the middle one is out.  But I use 
> variations of the top and bottom lines quite frequently, although in the 
> case of Inkey, calling Inkey with " " as the argument {a hard coded 
> constant} rather defeats the purpose.
> 
> In Euphoria, the sub would look different.  I'm going to use your code and 
> take a whack at it.
> 
> >Procedure Inkey(Integer Key)
> >     Key = get_key()
> >End Procedure
> >
> >Integer Key
> >
> >Inkey(Key)
> 
> Would this work?  If not this precisely, then how would it be coded, 
> precisely?  The difference isn't so much that I use a global variable for it
> 
> {Blech!} but that I pass a variable to it, and the variable is altered by 
> the Subroutine/Procedure and then passed back to the main program {if the 
> main program had a variable pointer in the first place}.
> 
> Love & Friendship & Blessed Be!
> Lynn Erika Kilroy

No, this wouldn't work because Euphoria doesn't use pointers and doesn't allow
you to modify a variable passed in as an argument.

Euphoria is case-sensitive, too, so "Integer" would not work in place of
"integer". Unless you defined "Integer" seperately.

--
"Actually, I'm sitting on my butt staring at a computer screen."
                                                  - Tom Tomorrow

j.