|
Re: Returning Values from Subroutines
by ignatz (Vicar) on Sep 06, 2002 at 15:17 UTC
|
One thing to know about Perl subroutines is that you don't need to specify a return value, since Perl automatically returns the last expression evaluated. So sometimes you'll see something like:
sub add{
my $value1 = $_[0];
my $value2 = $_[1];
my $result = ($value1 + $value2);
}
or
sub add{
my $value1 = $_[0];
my $value2 = $_[1];
($value1 + $value2);
}
or even
sub add{
($_[0] + $_[1]);
}
all of which return the same result.
I would probably do it as
sub add{
return ($_[0] + $_[1]);
}
so that it is clear what I am trying to return. But as the Scarecrow said, "People do tend to go both ways."
()-()
\"/
`
| [reply]
[d/l]
[select] |
Re: Returning Values from Subroutines
by TStanley (Canon) on Sep 06, 2002 at 14:39 UTC
|
sub main{
my $answer = &add(1,2);
print $answer;
}
sub add{
my $value1 = shift;
my $value2 = shift;
my $result = ($value1 + $value2);
return $result;
}
TStanley
--------
It is God's job to forgive Osama Bin Laden. It is our job to arrange the meeting -- General Norman Schwartzkopf | [reply]
[d/l] |
Re: Returning Values from Subroutines
by japhy (Canon) on Sep 06, 2002 at 14:45 UTC
|
Your add() function stores the sum in $result, but you're trying to return $answer. Replace return $answer with return $result in add(), and you'll be fine.
_____________________________________________________
Jeff[japhy]Pinyan:
Perl,
regex,
and perl
hacker, who'd like a job (NYC-area)
s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??; | [reply] |
Re: Returning Values from Subroutines
by derby (Abbot) on Sep 06, 2002 at 14:42 UTC
|
The relevant paragraph from perlsub:
The return value of a subroutine is the value of the last
expression evaluated. More explicitly, a "return" statement may be used to exit the subroutine, optionally specifying the returned value, which will be evaluated in the appropriate context (list, scalar, or void) depending on the context of the subroutine call. If you specify no return value, the subroutine returns an empty list in list context, the undefined value in scalar context, or nothing in void context. If you return one or more aggregates (arrays and hashes), these will be flattened together into one large indistinguishable list.
So yes, the way you show is one way to do it. err ... but return $result.
-derby | [reply] |
Re: Returning Values from Subroutines
by mojobozo (Monk) on Sep 06, 2002 at 14:51 UTC
|
Hey there. I'm not entirely sure why it's not working as is as I am but a novice, but the following works for me:
#!/usr/local/bin/perl
my $answer = &add(1,2);
print $answer;
sub add{
return $result = ($_[0] + $_[1]);
}
As far as the original not working, will the initial sub ("main") even run without a call to it? I tried running it with a call for it and got an error. Also, in the the "add" sub, you are returning $answer, but it was never assigned a value in the sub.
Anyone else want to chime in? I'd like to hear more on this one as well.
mb++
was hoping to get first return, but was beat out by six minutes... curses! | [reply]
[d/l] |
|
|
A little more golf on this one:
#!/usr/local/bin/perl
print add(1,2);
sub add{
return $result = ($_[0] + $_[1]);
}
Unless, of course, you wanted to save the value returned.
mb | [reply]
[d/l] |
|
|
And, using the example in ignatz's reposnse, even more strokes shaved:
#!/usr/local/bin/perl
print add(1,2);
sub add{
return ($_[0] + $_[1]);
}
Man, this is getting fun. I wish I could shave this many strokes of my discgolf game!
_____________________________________________
mojobozo
word (wûrd)
interj. Slang. Used to express approval or an affirmative response to
something. Sometimes used with up. Source | [reply]
[d/l] |
|
|
|
|
|
|
# 123456789
sub add{pop()+pop}
— Arien | [reply]
[d/l] |
Re: Returning Values from Subroutines
by fglock (Vicar) on Sep 06, 2002 at 14:40 UTC
|
your sum is in $result, so return $result
update: no need for '&' before add
| [reply] |