How to declare arrays and scalars together?

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: How to declare arrays and scalars together? by ikegami (Patriarch) on Jun 18, 2012 at 05:17 UTC
First, `( (),(),"0", () )` is the same as `"0"`. Second, no matter what list the right-hand side of the assignment returns, nothing will ever be assigned to `$var`. Everything will be assigned to `@arr1`. There's no way for the assignment to know how many elements of the list should be assigned to @arr1, how many to @arr2, etc. If you're not assigning anything to more than one array, you can do what you want by moving the scalars to before the arrays. `my ($var, @arr1, @arr2, @arr3) = "0";` [download]	[reply] [d/l] [select]
Re: How to declare arrays and scalars together? by cheekuperl (Monk) on Jun 18, 2012 at 05:18 UTC
As such, nothing looks/IS wrong in your code. It's just that it does not work the way you are thinking it would. `my (@arr1, @arr2, $var, @arr3) = ( (1,2),(11,22),"0", () ); print "\n[@arr1]"; print "\nvar is $var";` [download] RHS of first line is flattened into a single list and copied in its entirety into @arr1. All other elements in LHS of first line are empty. Remember why you can not pass multiple arrays to a subroutine?	[reply] [d/l]
Re^2: How to declare arrays and scalars together? by 2teez (Vicar) on Jun 18, 2012 at 05:36 UTC
"Remember why you can not pass multiple arrays to a subroutine?" except, one uses reference like so: `my $arr1_ref = [ 1, 2, 3 ]; my $arr2_ref = [ 10, 9, 8, 7 ]; load_arr( $arr1_ref, $arr2_ref ); ## load multiple array references sub load_arr { my ( $arr1_def, $arr2_def ) = @_; print join "\n", @{$arr1_def}, @{$arr2_def}; return; }` [download]	[reply] [d/l]
Re^3: How to declare arrays and scalars together? by Anonymous Monk on Jun 18, 2012 at 16:49 UTC
You're passing array references there, not arrays.	[reply]
Re^4: How to declare arrays and scalars together? by 2teez (Vicar) on Jun 18, 2012 at 19:32 UTC
Re^5: How to declare arrays and scalars together? by Anonymous Monk on Jun 19, 2012 at 01:59 UTC
Re: How to declare arrays and scalars together? by frozenwithjoy (Priest) on Jun 18, 2012 at 05:28 UTC
If all you are trying to do is initialize these variables, use: `my (@arr1, @arr2, $var, @arr3);`	[reply] [d/l]
Re^2: How to declare arrays and scalars together? by ikegami (Patriarch) on Jun 18, 2012 at 05:30 UTC
That declares them and initialises them to empty or undef. He wants to initialise `$var` to zero at the same time.	[reply] [d/l]
Re^3: How to declare arrays and scalars together? by frozenwithjoy (Priest) on Jun 18, 2012 at 05:40 UTC
Ah yes. I spaced over that part. Too much traveling this weekend! Thanks. Note to OP: I recommend using two lines to do what you want to do. For example... `my ( @arr1, @arr2, @arr3 ); my $var = 0;` [download] is quite a bit more readable than: `my ( $var, @arr1, @arr2, @arr3 ) = 0;` [download]	[reply] [d/l] [select]