1. Return Statement Usage
- Posted by Alan Tu <ATU5713 at COMPUSERVE.COM>
Jun 23, 1998
-
Last edited Jun 24, 1998
I have two questions about the return statement.
1. If I have a main program, and I call a global procedure within an
include file, do I need to put return at the end of the global procedure?=
2. In the same set of procedures, in the global procedure, which is in t=
he
include file, I call a local procedure that is in the same include file. =
Do I need to put return at the end of the local procedure to continue wit=
h
the main procedur?
In general, under what circumstances should one use return at the end of =
a
procedure to keep the program from "wandering off"?
--Alan
=
2. Re: Return Statement Usage
- Posted by Joe Phillips <bubba at TXWES.EDU>
Jun 23, 1998
-
Last edited Jun 24, 1998
In all situations the end of procedure returns to the calling point.
(Wherever that was.) If you called a global, then it returns to where you
called it from. If you call a local, that procedure would return to the
point from which it was called.
While I do not know the internals of Euphoria, I suspect the return address
is pushed onto a stack that is LIFO. That is, last one on the stack is the
first one off. This would allow the program to always know "..from whence
it came." I also suspect an end of procedure actually executes a return
statement.
The exception is code in an include file that is not within a procedure,
that would run at program start and fall down to whatever other code was
not in a procedure. (ie - your actual main loop somewhere in your program.)
However, you would never be able to "call" that "renegade'" code as it has
no entry point. [ Actually, you COULD call it renegade code, I don't think
any one would care ! ]
At 10:53 PM 6/23/98 -0400, you wrote:
>I have two questions about the return statement.
>
>1. If I have a main program, and I call a global procedure within an
>include file, do I need to put return at the end of the global procedure?
>
>2. In the same set of procedures, in the global procedure, which is in the
>include file, I call a local procedure that is in the same include file.
>Do I need to put return at the end of the local procedure to continue with
>the main procedur?
>
>In general, under what circumstances should one use return at the end of a
>procedure to keep the program from "wandering off"?
>
>--Alan
>
>
Joe Phillips, Assistant Director
Information Technology Services
Texas Wesleyan University 817-531-4284
3. Re: Return Statement Usage
Alan Tu wrote:
> I have two questions about the return statement.
>
> 1. If I have a main program, and I call a global procedure within an
> include file, do I need to put return at the end of the global procedure?
>
Never use return in a procedure. A procedure does a job (procedure) and
returns by itsel.f.Always use a return at the end of a function. (A function
must return somthing to it's caller.)
Procedures do stuff until they hit the "end procedure" statement,
while functions can return before they get to the "end function",
A function can have several "return" statements, based on different tests:
function avg_days_pay (atom weekly_pay, atom days_worked)
if days_worked < 1 then return 0 -- can't divide by zero, so answer would be
meaningless
else return weekly_pay / days_worked
end if
end function
> 2. In the same set of procedures, in the global procedure, which is in the
> include file, I call a local procedure that is in the same include file.
> Do I need to put return at the end of the local procedure to continue with
> the main procedur?
>
> In general, under what circumstances should one use return at the end of a
> procedure to keep the program from "wandering off"?
>
> --Alan
4. Re: Return Statement Usage
Irv wrote:
> Never use return in a procedure. <snip>
According to Robert, the use of return statements as alternative exit
points from procedures has been, and always will be supported. It is a
very handy feature, e.g. in certain kinds of recursion. Jiri
5. Re: Return Statement Usage
- Posted by Daniel Berstein <daber at PAIR.COM>
Jun 24, 1998
-
Last edited Jun 25, 1998
-----Original Message-----
De: Irv <irv at ELLIJAY.COM>
Para: EUPHORIA at cwisserver1.mcs.muohio.edu
<EUPHORIA at cwisserver1.mcs.muohio.edu>
Fecha: miércoles 24 de junio de 1998 1:06
Asunto: Re: Return Statement Usage
>Never use return in a procedure. A procedure does a job (procedure) and
>returns by itsel.f.Always use a return at the end of a function. (A
function
>must return somthing to it's caller.)
>Procedures do stuff until they hit the "end procedure" statement,
>while functions can return before they get to the "end function",
>A function can have several "return" statements, based on different tests:
A procedure can also have several "return" statements. The only thing is
that a procedure can't return a value. It's ilegal to say: return foo,
within a procedure. Having return statements inside procedures is quite
useful indeed.
Regards,
Daniel Berstein
daber at pair.com
