I re-looked at your original code and my brain hurts!

It is of course possible to use indices to access a 2-D array in Perl, however this is not the normal situation. A far, far more normal situation is to access each row as an array of values. This is also true in C albeit with different syntax than this.

I re-wrote your code below.
These integer index buddies of i and j just don't appear that often in Perl code. Of course Perl allows that syntax. Note that by "not often", I do not mean "never". The most common errors in programming are memory allocation errors and "off by one" errors when using array indices or when looping. Perl for the most part takes care of memory allocation for you in a very efficient way - you don't have to worry about it unless you are doing something really fancy. This "off by one error" stuff can be much more problematic. In general don't use i or j indices unless you have to.

#!/usr/bin/perl
use strict;
use warnings;

my @AoA;
                    
while (my $line = <DATA>) 
{
   my @tmp = split ' ',$line;    
   push @AoA, [ @tmp ];    
}


## Print the totals for each line ###
## and the final grand_total      ###   

my $grand_total;

foreach my $row_ref (@AoA)
{
    my $line_total;
    
    foreach my $num (@$row_ref)
    {
       $line_total += $num;
    }
    
    print "Line Total: $line_total\n";
    $grand_total += $line_total;
}

print "Grand Total: $grand_total\n";

=Prints:
Line Total: 150
Line Total: 75
Line Total: 55
Grand Total: 280
=cut

    
__DATA__
10 20 30 40 50
15 25 35
1 2 3 4 5 6 7 8 9 10
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