How do I initialize an array to 0?
I have tried this.
my @arr = ();
But it always throws me a warning, "Use of uninitialized value". I do not know the size of the array beforehand. I fill it dynamically. I thought the above piece of code was supposed to initialize it to 0.
How do I do this?
This question is related to
perl
arrays
initialization
To produce the output in your comment to your post, this will do it:
use strict;
use warnings;
my @other_array = (0,0,0,1,2,2,3,3,3,4);
my @array;
my %uniqs;
$uniqs{$_}++ for @other_array;
foreach (keys %uniqs) { $array[$_]=$uniqs{$_} }
print "array[$_] = $array[$_]\n" for (0..$#array);
Output:
array[0] = 3
array[1] = 1
array[2] = 2
array[3] = 3
array[4] = 1
This is different than your stated algorithm of producing a parallel array with zero values, but it is a more Perly way of doing it...
If you must have a parallel array that is the same size as your first array with the elements initialized to 0, this statement will dynamically do it: @array=(0) x scalar(@other_array);
but really, you don't need to do that.
What do you mean by "initialize an array to zero"? Arrays don't contain "zero" -- they can contain "zero elements", which is the same as "an empty list". Or, you could have an array with one element, where that element is a zero: my @array = (0);
my @array = ();
should work just fine -- it allocates a new array called @array
, and then assigns it the empty list, ()
. Note that this is identical to simply saying my @array;
, since the initial value of a new array is the empty list anyway.
Are you sure you are getting an error from this line, and not somewhere else in your code? Ensure you have use strict; use warnings;
in your module or script, and check the line number of the error you get. (Posting some contextual code here might help, too.)
Source: Stackoverflow.com