Hash of arrays question

[StoneSoup]

So, I have a hash of array. The hash and arrays are initialized without a given length, so both are supposed to expand. I have isolated my problem to the latter 2 of the following three lines.

my $oldLength = @hash{$level};
$hash{$currentLevel}[$oldLength]=$var1;
$hash{$currentLevel}[$oldLength+1]=$var2;

In the case where I have to expand an array that has already been made before, everything fails, but if I constantly increase my $currentLevel (and therefore make new arrays) everything seems to work. Is there a small problem that I am missing here?

Thanks

 

[KevinADC]

use push() to add data to the end of an array, unshift() to add data to the beginning of an array.

------------------------------------------
- Kevin, perl coder unexceptional!

 

[StoneSoup]

It gives an error saying that you cannot put in a slice of a hash. Well it did when I used push

 

[KevinADC]

well, this looks wrong:

my $oldLength = @hash{$level};

maybe that should be:

my $oldLength = @{$hash{$level}};

in which case:

push @{$hash{$level}},'foo';

------------------------------------------
- Kevin, perl coder unexceptional!

 

[PinkeyNBrain]

Double check how your using your vars - try running the following and see if you get what you expect

#!/usr/bin/perl

$hash{'a'}[0] = 'a0' ;
$hash{'a'}[1] = 'a1' ;
$hash{'a'}[2] = 'a2' ;
$hash{'a'}[3] = 'a3' ;
$hash{'b'}[0] = 'b0' ;
$hash{'b'}[1] = 'b1' ;

$level = 'a' ;
$oldLength = @hash{$level};
print "len $level = $oldLength\n";

$level = 'b' ;
$oldLength = @hash{$level};
print "len $level = $oldLength\n";

$level = 'a' ;
$oldLength = @{$hash{$level}};
print "len $level = $oldLength\n";

$level = 'b' ;
$oldLength = @{$hash{$level}};
print "len $level = $oldLength\n";

 

[KevinADC]

Nice examples Pinkey.

------------------------------------------
- Kevin, perl coder unexceptional!

 

[StoneSoup]

Kevin, I tried what you said and I got this error:
"Can't use an undefined value as an ARRAY reference

 

[KevinADC]

one of your variables is not defined. See Pinkeys code and you see it works.

------------------------------------------
- Kevin, perl coder unexceptional!

 

[StoneSoup]

$level is defined in my code. I redid the length line as you recommended, but now I get no output at all.

 

[KevinADC]

post your code and let us know what $level is

------------------------------------------
- Kevin, perl coder unexceptional!

 

[StoneSoup]

before this there is a while loop and $level is initialized before that. $level is like a counter so it is incremented each time the while loop executes. Would there be a problem if $hash{$level} is undefined and I am trying to get the length of that undefined array?

 

[KevinADC]

probably

------------------------------------------
- Kevin, perl coder unexceptional!