#!/usr/bin/perl
$filename = time();

if(!open(TEXTFILE, "> temp_datafile")) {
    print STDERR "Can't open file";

}

@alphabet = ('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z');

for ($i=0; $i<26; $i++) {

$arr[$i] = "$alphabet[$i]\t0";

}


if(!open(TEXTFILE2, "@ARGV")) {
    print STDERR "Can't open file";

}

if(!open(TEXTFILE3, "> $filename")) {
    print STDERR "Can't open file";

}

while ((read(TEXTFILE2, $buf, 1)) != EOF) {

    if ($buf =~ /[a-zA-Z]/) {

	$buf =~ tr/A-Z/a-z/;

	for ($i=0; $i<26; $i++) {

	    if ($arr[$i] =~ /$buf/) {

		($alpha, $freq) = split(/\t/, $arr[$i]);
		$freq++;
		$arr[$i] = "$alpha\t$freq";
	    }
	}
    }
}

for ($i=0; $i<26; $i++) {
    ($alpha, $freq) = split(/\t/, $arr[$i]);
    $alpha2 = $alpha;
    $alpha = $i + 1;
    $arr[$i] = "$alpha\t$freq";
    $arr2[$i] = "$freq\t$alpha2";
    print TEXTFILE "$arr[$i]\n";

}
	print "The highest frequency of letters is:-\n";

sub numerically { $a <=> $b }
@arr3 = reverse sort numerically @arr2;
for ($i=0; $i<26; $i++) {
    ($freq, $alpha) = split(/\t/, $arr3[$i]);
    $arr3[$i] = "$alpha\t$freq";
    print TEXTFILE3 "$arr3[$i]\n";

    if ($i < 13) {
	print "$arr3[$i]\n";
}

}