How to assign array variable as a hash? - arrays

Question

I'm trying to print this hash. As key1 is the array[0], key2 is array[2] and $sum[0] is the value. But the has does not work. What I'm doing wrong?
#array=(10,45,20);
#sum=($array[0]+$array[1]+$array[2]);
%hash;
$hash{$array[0]}{$array[2]}=$sum[0]
At the end of the hashes I want to print 10 : 75 to the screen.

Answer 1

You've set
$hash{$array[0]}{$array[2]} = $sum[0]
which with the given values is
$hash{10}{20} = 75
If you want to print 10 : 75 from the hash then you need to write
printf "%d : %d\n",10, $hash{10}{20}
And while I'm sure you want something more general than that, you really haven't given enough information

Answer 2

From the description you gave to #ikegami «my program will accept ...» I created a file that would have the data:
data_1.txt:
john 10 45 20
alex 30 15 12
pete 23 45 10 21
will 06 56
bob 8 12 3
lazy
note that only the first two lines actually match the description, I'll come back to that later.
sum.pl:
use strict;
use warnings;
use List::Util 'sum';
# get the two filenames it should work with
#
my $filename_1 = shift;
my $filename_2 = shift;
# be sure we read a file for most modern systems, UTF-8
#
open( my $file1, '<:encoding(UTF-8)', $filename_1)
or die "Can't open file: $filename_1";
# create the (empty) data structure
#
my %sums_and_names;
#
# the % in perl means you are talking about a hash,
# use a sensible name instead of 'hash'
# read line by line
while ( my $line = <$file1> ) {
chomp $line; # get rid of the line endings
my ($name, #grades) = split ' ', $line;
#
# this is not strictly doing what you asked for, just more flexible
#
# split on ' ', a space character, splits on any asmount of (white) space
# your task said that there is one space.
# strictly, you could should split on / /, the regular expression
#
# the first part will go into the variable $name, the rest in array #grades
# strictly you have only three grades so the following would do
# my ($name, $grade_1, $grade_2, $grade_3) = split / /, $line;
my $sum = sum(#grades) // 'no grades';
#
# since we now can handle any number of grades, not just three, we could
# have no grades at all and thus result in `undef`
#
# using the function sum0 would return the value 0 instead
#
# you'll get away with the `undef` using in a hash assignment,
# it will turn it into an empty string `''`
=pod
$sums_and_names{foo}{bar} = [ 'baz', 'qux' ];
=cut
#
# here is where your task doesn't make sense
# i am guessing:
#
$sums_and_names{$sum}{$name} = \#grades;
#
# at least we have all the data from filename_1, and the sum of the grades
}
# please decide on what you want to print
use Data::Dumper;
print Dumper \%sums_and_names;
and running perl sum.pl data_1.txt data_2.txt will give you something like
output:
$VAR1 = {
'no grades' => {
'lazy' => []
},
'23' => {
'bob' => [
'8',
'12',
'3'
]
},
'57' => {
'alex' => [
'30',
'15',
'12'
]
},
'62' => {
'will' => [
'06',
'56'
]
},
'75' => {
'john' => [
'10',
'45',
'20'
]
},
'99' => {
'pete' => [
'23',
'45',
'10',
'21'
]
}
};
please note, strictly the block inside the while loop could had been written as:
chomp $line;
my ($name, $grade_1, $grade_2, $grade_3) = split / /, $line;
$sum = $grade_1 + $grade_2 + $grade_3;
$sums_and_names{$sum}{$name} = [ $grade_1, $grade_2, $grade_3 ];
but I quote from #Borodin:
And while I'm sure you want something more general than that, you really haven't given enough information

Answer 3

Always use use strict; use warnings qw( all );!!!
There's only one sum (at a time), so don't need an array.
There's no need for a hash of hash; a simple hash will do.
Fixed:
use strict;
use warnings qw( all );
use List::Util qw( sum );
my %hash;
while (...) {
my #nums = ...;
$hash{ $nums[0] } = sum(#nums);
}
for (sort { $a <=> $b } keys(%hash)) {
print("$_: $hash{$_}\n");
}