Some other resources: perlre, perlretut, perlrecharclass, Regexp Quote-Like Operators, and Pattern Matching, Regular Expressions, and Parsing.

Also see Short, Self Contained, Correct (Compilable), Example and How to ask better questions using Test::More and sample data. For the latter, both for asking questions and for general development, maybe something like:

use warnings;
use strict;

use Test::More 'no_plan';
use Test::NoWarnings;

my @TESTS = (
  # dirty                               # clean
  [ q{The 99th bottle's x-o-x labels'} => q{The 99th bottle's labels'}
+ ],
  ...
  );

VECTOR:
for my $ar_vector (@TESTS) {

  if (not ref $ar_vector) {
    note $ar_vector;
    next VECTOR;
    }

  my ($dirty, $expected) = @$ar_vector;

  my $clean = clean_it_up($dirty);
  ok $clean eq $expected, qq{'$dirty' -> '$clean'};
  
  }  # end for VECTOR

done_testing;

exit;

# subroutine(s) ##############################

sub clean_it_up { ... }

...
[download]

Update: Changed to using q{...} in example code test sentences (was '...') because it's more compatible with embedded single-quotes. (Also a trivial wording change.)

Hi, $help ne $doing_it_for_you. What have you tried?

(Update: Also posted a link to perlrequick in CB in response to OP)

I, too, believe that what you want is a regex. I also agree with 1nickt that this isn't a code writing service. Assuming from your uncertainty that you are unfamiliar with regexes - a terrifyingly complex subject - let me try to get you started.

Character classes seem to be what you want. There are lots of resources on line, for example https://www.regular-expressions.info/charclass.html. You may or may not need different classes for each of your parts. A class for letters, digits and the other three you mention might be:

[a..z0..9'-_]
[download]

Using i after the final slash will make the regex case insensitive, meaning that you don't need to include upper case letters as well.

If you are familiar with testing, I recommend writing this as a series of tests to build up the regex one requirement at a time. Your test file will then explain to you in six months' time what you were trying to do. You won't remember otherwise. If you aren't, testing is a very useful tool to learn.

Regards,

John Davies

if( 
    m[
        ^'?[a-z]                      ## start with letter or an apost
+rophy followed by one
        [a-z0-9'-_]+                  ## Alphanumeric + '-_
        (?[a-z0-9] | s') $            ## ends with alphanumeric or 
    ]x
    and not
    m[''|--]
}{
    ## Ok!
}
[download]

Nice! At first I thought what a shame it was that you would provide code-writing service for someone who showed no effort, but then I realised you were really providing code that does not compile, so as to force the OP to show effort. Sneaky!



The way forward always starts with a minimal test.

... so as to force the OP to show effort.

And if you'd kept that to yourself, we might have found out if the OP had tried it.

With following the error messages and just a little effort, what I posted can become:

#! perl -slw
use strict;

for( qw[
    ab123
    'ab123s
    'ab123's
] ) {
    if(
        m[
            ^'? [a-z]               ## start with letter or an apostro
+phy followed by one
            [a-z0-9'-_]+            ## Alphanumeric + '-_
            (?: [a-z0-9] | s') $    ## ends with alphanumeric or s'
        ]x
        and not
        m[''|--]                    ## No doubled ''s or --s
    ){
        print "$_: Ok!";
    } else {
        print "$_: Bad!";
    }
}
__END__
C:\test>junk
ab123: Ok!
'ab123s: Ok!
'ab123's: Ok!
[download]

Which gives a starting point but not the whole thing.

If you're going to bother saying something, best make it something useful.

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority". The enemy of (IT) success is complexity.

In the absence of evidence, opinion is indistinguishable from prejudice. Suck that fhit

I'm looking for a regex (at least I think what is most likely a regex)

Besides, you did not clearly specify whether you just want to validate that the text used satisfies your requirements, or whether you actually want to clean up the piece of text (i.e. remove characters that violate your requirements).