#!/usr/bin/perl -w

# counts the instances of each character in the file specified.

my %ascii_counts = ();
my @keys = keys(%ascii_counts);
my @values = values(%ascii_counts);
my $total_chars;

while (1) {
# program's main loop
&init_hash();
&fill_hash();
&clean_hash();
&print_hash();
}

# Subroutines ==========================================================

sub init_hash {
# foreach ascii character add it to the hash with count = 0
foreach $i (0..255) {
$ascii_counts{ord($i)} = 0;
}
}

sub fill_hash {
# get filename
print "Enter 'ls' or a filename to scan: ";
my $file_name = shift || ;
while ($file_name =~ m/^ls/) {
system("$file_name");
print "\nEnter 'ls' or a filename to scan: ";
$file_name = ;
}

# open file
open(INFILE, $file_name) or warn &fill_hash();

# iterate through lines/characters incrementing the key's value
while (my $l = ) {
my @line = split(//, $l);
foreach $char (@line) {
$ascii_counts{$char}++;
}
}

# close file
close(INFILE);
}

sub clean_hash {
while (my ($key, $value) = each(%ascii_counts)) {
# remove keys with value == 0
if ($value == 0) {
delete($ascii_counts{$key});
}
# remove non-alpha-numeric keys
elsif ($key =~ /\W/) {
delete($ascii_counts{$key});
}
}
# store the key/value pairs sorted for later use
@keys = sort(keys(%ascii_counts));
@values = sort(values(%ascii_counts));

# determine total number of values
$total_chars = 0;
foreach $x (@values) {
$total_chars += $x;
}
}

sub print_hash {
print "\n[key]\t[count]\t[%]\n\n";

foreach my $key (@keys) {
my $value = $ascii_counts{$key};
my $percent = $value/$total_chars*100;
print " $key\t$value\t$percent\n";
}

print "\nTotal: $total_chars characters.\n\n";
}