On 11/01/2011 03:02 PM, rent0n wrote:
Hi all,
Can somebody please explain what is the difference between:
sub subroutine {
my $var = @_;
that puts @_ in a scalar context which returns the number of elements in
an array.
...
return 1;
}
and:
sub subroutine {
my ($var) = @_;
...
that puts @_ in a list context which returns its elements in a list. the
first element is assigned to $var.
return 1;
}
I think it's something related to the context but I'm not completely
sure. What I know is that to have the behaviour I want I have to declare
the variable like in the second example (with parentheses).
This confuses me a bit because it's not the way I usually declare
variables in my main program (that is, without parentheses).
it is context as you surmised. the reason you see it differently has
nothing to do with subs or @_. it is that you are likely declaring your
file scoped variables without initializing them. it is the assignment
that is making the difference and not the sub. if you did this outside a
sub it would have the same problem as in the sub:
my $foo = @bar ;
so just always use parens around the my list when you assign @_ to them
and you will be fine. it is the standard idiom for getting args inside a
sub.
Please assume I'm 5 years old.
now go sit in the corner for 10 minutes or until you learned your lesson
here! read more about context in perldata. :)
uri
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