BTW when you want to join two strings, use a dot ., not a plus +. (This is called "concatenation").

Doh! Thanks. Back to the drawing board :(

What should I be using instead of TR?

You can use tr, but you have to discard its return value.

my $str = "ab c,d.e";
$str =~ tr/ ,.//;
# here $str is "abcde"
[download]

So you need to use the modified string after the tr. And don't try to stuff it all in one line ;-)

(Update: fixed match operator)

use strict;
use warnings;

my $lines    = 0;
my $mystring = '';
my $chars    = 0;
my $word_cnt = 0;

while(<DATA>) {
    my $str = $_;
    $chars += length($str);
    $lines++ ;
    my @words = grep /\w/, ($str =~ /\b\w*\b/g);
    $word_cnt += $#words + 1;
    $str =~ s/( |,|\.|\n|\t)//g;
    $mystring .= lc($str);
}

print "Lines: $lines\n";
print "Words: $word_cnt\n";
print "Characters: $chars\n";
print "Total String: $mystring\n";

__DATA__
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
The quick brown fox jumps over the lazy dog.
[download]

Lines: 4
Words: 36
Characters: 180
Total String: thequickbrownfoxjumpsoverthelazydogthequickbrownfoxjumps
+overthelazydogthequickbrownfoxjumpsoverthelazydogthequickbrownfoxjump
+soverthelazydog
[download]

THANKYOU very much, I see where I was going wrong now.

The split in

my @word = split " ", $_;
[download]

my @words = 
    map { lc }          # convert to lower case
    split /[\s.]+/, $_; # split on white space and "."
[download]

No I still can't get it to work. I just need to combine the contents of the file removing all white spaces, tabs, commas, return characters and periods.

E.g

Hey, diddle, diddle,
The cat and the fiddle,
heydiddlediddlethecatandthefiddle

You hadn't mentioned commas in the original post. Anyway to show that the approach works a complete program

#!/usr/bin/perl 
use 5.010_000;
use warnings;
use strict;

my %number_of;
my @words;

while ( my $line = <DATA> ) {
    $number_of{lines}++;
    $number_of{chars} += length $line;
    push @words, map { lc } split /[\s.,]+/, $line;
}
$number_of{words} = scalar @words;

foreach my $item (qw(chars words lines)) {
    say "Number of $item: $number_of{$item}";
}
say @words;

__DATA__
Hey, diddle, diddle,
The cat and the fiddle,
The cow jumped over the moon.
[download]

and the output

Number of chars: 75
Number of words: 14
Number of lines: 3
heydiddlediddlethecatandthefiddlethecowjumpedoverthemoon
[download]

If other punctuation is to be removed then you add it to the split. The difficulty would be with an apostrophe, you probably do not want to count don't as two words so the split line becomes

push @words, map { lc } # change to lower case
    map { tr/'//d; $_ } # remove apostrophes
    split /[\s.,?!"]+/, # split on space and punctuation
    $line;
[download]

Update: removed a useless use List::Util; from the example.

# replace (s///) all (g) non word-characters \W with nothing
$mystring = $mystring += $_=~ s/\W//g;
print lc($mystring);  # lowercase
[download]

Thanks for the help so far everybody!

I tried this, $mystring seems to return 31 instead of the formatted string.



open (READFILE, "<poem.txt") || die "Couldn't open file: $!";
$buffer = "";
$lines = 0;

while(<READFILE>) {
    $chars += length($_);
    $lines++ ;
    my @word = split " ", $_;
    $word_cnt += @word;
    chomp($mystring);
$mystring = $mystring += $_=~ s/\W//g;
     
}

print ("Lines: $lines\n");
print ("Words: $word_cnt\n");
print ("Characters: $chars\n");

print lc("$mystring\n");
[download]

Because despite being told that s modifies the string it's working on in place you persist in attempting to use its return value (the number of substitutions made) as something meaningful ($_ contains the converted string; you would want to append the contents of $_ to your accumulated buffer instead). Not to mention you're still trying to use + as a concatenation operator rather than the correct . operator.

Update: Oop, you're using s/// instead of tr/// but the point's the same (that it modifies the string in place and doesn't have a meaningfull (in this instance) return value). Wording changed accordingly.

And it's just been pointed out to me that that line wasn't yours, which only partly excuses you in that you cargo cultly included it without understanding that it was doing the very thing you'd already been warned about.

The cake is a lie.
The cake is a lie.
The cake is a lie.

Hi,
almost there...


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

my ($chars, $lines, @word, $word_cnt, $mystring, $bla );

$lines = 0;

while(<DATA>) {
    $chars += length($_);
    $lines++ ;
    my @word = split " ", $_;
    $word_cnt += @word;
    ($bla = $_) =~ s/\W//g; # assign the converted string of $_ to $bl
+a
     $mystring .= lc($bla); # concatenate lowercase $bla to $mystring
}

print ("Lines: $lines\n");
print ("Words: $word_cnt\n");
print ("Characters: $chars\n");

print("Total String: $mystring \n");

__DATA__
Hey, diddle, diddle,
The cat and the fiddle.
[download]


Regards,
svenXY

Actually, that wouldn't solve the problem.
Using tr was a good suggestion when Slug wanted to count the characters, but in this case he just wants to eliminate them.
From the documentation

If the REPLACEMENTLIST is empty, the SEARCHLIST is replicated. This latter is useful for counting characters in a class or for squashing character sequences in a class.

So nothing would be replaced.

You are right, of course, on the '.=' operator.