The Perl 5 Project

#!/usr/bin/env perl
#
# $Id: sol4-17.pl,v 0.05 2024/04/05 16:19:18 kc4zvw Exp kc4zvw $

use 5.036_003;
use strict;
use warnings;

# fisher_yates_shuffle( \@array ) : generate a random permutation
# of @array in place

sub fisher_yates_shuffle {
        my $array = shift;
        my $i;

        for ($i = @$array; --$i;) {
                my $j = int rand ($i + 1);
                next if $i == $j;
                @$array[$i, $j] = @$array[$j, $i];
        }
}


####################
### main program ###
####################

my @array = qw/ 1 2 3 4 5 6 7 8 9 10 11 12 /;
my $path_to_file = "alpha.txt";
my $handle;

unless (open $handle, "<:encoding(ascii)", $path_to_file) {
        print STDERR "Could not open file '$path_to_file': $!\n";
        # we return 'undefined', we could also 'die' or 'croak'
        die "No reason to continue : $!\n";
        #return undef
}


chomp(my @lines = <$handle>);

unless (close $handle) {
        # what does it mean if close yields an error and you are just reading?
        print STDERR "Don't care error while closing - '$path_to_file'.\n";
        warn "contining - $!\n";
}

# assuming @array is your array:
print join(", ", @array);
print "\n";
fisher_yates_shuffle(\@array);
print join(", ", @array);
print "\n\n";

# assuming @a is your array:
my @a = qw(abc def ghi jkl mno pqr stu vw xyz);
print "@a";
print "\n";
fisher_yates_shuffle(\@a);
print "@a";
print "\n\n";

# assuming @lines is your array:
print "@lines";
print "\n";
fisher_yates_shuffle(\@lines);
print "@lines";
print "\n\n";

# End of File

  

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
8, 12, 7, 11, 9, 4, 3, 10, 2, 1, 6, 5

abc def ghi jkl mno pqr stu vw xyz
stu abc mno pqr vw jkl ghi def xyz

alpha bravo charlie delta echo foxtrot golf hotel india
foxtrot echo hotel india bravo delta alpha golf charlie