How to print an array in a matrix format - perl

Question

I am creating a cypher program. I want to transcript the key (given in $ARGV[1]) to a matrix of numbers.
But, I have some troubles figuring out how to print the array as a matrix without getting warnings/errors.
use strict;
use warnings;
use POSIX;
my #characters = split //, $ARGV[1];
#characters = map {ord($_)} 0 .. $#characters;
my $col_nb = ceil(sqrt($#characters));
for my $i (1 .. ($col_nb**2 - $#characters - 1)) { push #characters , 0; }
foreach my $i (0 .. $col_nb - 1) {
printf "%.0f\t" x $col_nb, #characters[$col_nb * $i .. $col_nb * ($i + 1)];
printf("\n");
}
I am triyng to get an output like this : (key = "abcd")
48 49
50 51
But, I get these errors on the output :
Redundant argument in printf at test.perl line 9.
48 49
Redundant argument in printf at test.perl line 9.
50 51

Answer 1

You are off by one. Your array slice contains 3 numbers, but you only want 2. Change:
printf "%.0f\t" x $col_nb, #characters[$col_nb * $i .. $col_nb * ($i + 1)];
to:
printf "%.0f\t" x $col_nb, #characters[$col_nb * $i .. ($col_nb * ($i + 1) - 1)];
You can add use diagnostics; to get a more verbose warning message:
(W redundant) You called a function with more arguments than other
arguments you supplied indicated would be needed. Currently only
emitted when a printf-type format required fewer arguments than were
supplied, but might be used in the future for e.g. "pack" in perlfunc.
Only use printf when you are doing formatting. Change:
printf("\n");
to:
print "\n";

Answer 2

Check the edge cases and off-by-one errors.
Also, you want the square root of the number of characters, not the number - 1.
Moreover, you don't need to create another array to hold the numbers, you can map the characters to them on the fly when printing.
#!/usr/bin/perl
use strict;
use warnings;
use POSIX qw{ ceil };
my #characters = split //, $ARGV[1];
my $col_nb = ceil(sqrt #characters);
for my $i (0 .. $col_nb - 1) {
printf "%d\t" x $col_nb,
map defined ? ord : 0,
#characters[$col_nb * $i .. $col_nb * ($i + 1) - 1];
print "\n";
}