Hello perlynewby,

First off, it’s good that you use strict; but you should always use warnings; as well.

Now, in this regex:

/^(.*)+([^ ]+)$/
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the characters * and + are both quantifiers, meaning they tell the regex engine how many of the preceding entity it should try to match. * means zero or more, and + means one or more. So the construct (.*)+ means: match zero or more non-newline characters zero or more times, and do this one or more times. Which doesn’t make a lot of sense. See “Quantifiers” in perlre#Regular-Expressions and consider carefully which quantifier you need.

As stevieb has explained, these quantifiers are greedy, meaning the regex engine will try to match as many characters as possible and stop looking after the longest successful match. To make the quantifiers non-greedy, append a ?:

use strict;
use warnings;

my @original_names =
(
    'Fred Flintstone',
    'Leonardo da Vinci ',
    'Raffaello da Urbino',
);

my @cognome = last_name_first(@original_names);

print join(';', @cognome);

sub last_name_first
{
    my @names = @_;

    for (@names)
    {
        s/\s+$//;
        s/^(.*?)(\S+)$/$2, $1/;
        s/\s+$//;
    }

    return @names;
}
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Output:

17:14 >perl 1308_SoPW.pl
Flintstone, Fred;Vinci, Leonardo da;Urbino, Raffaello da
17:14 >
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Note that the above script also removes trailing whitespace from the last and first names. In the former case, the whitespace might be there; in the latter case, it is certain to be. The character class \S matches any non-whitespace character.

Hope that helps,

Athanasius, these are great details. I am sure I will make more mistakes with these literal greedy regex matching. I thought it'd be a nice way to get my hands dirty here...I did and learned and more to practice.

will try the advice given to a regex enginee provide to me here

Thank you Sir!

Read the Perl perlretut, especially the part on character classes. You probably want a common class like \w.

Your first regexp matches everything up until the second one matches.

It's a good use of your time to stop what you are doing, take 30 minutes, and read and understand the tutorial !

Update: links to docs

in the end, my solution was to use \w to get the regex to properly capture on the string for first name and last names...but

I did read the tutorials on regex and still unable to understand it how the space there worked

thanks

Because without the space, you are capturing EVERYTHING (.*) INCLUDING spaces, up until the very last non-whitespace character in the string. Without the space, the regex doesn't know to stop at a space.

I always use \s+ in place of literal spaces. I find it makes the regex far easier to understand, and way less likely I'll overlook a literal space (which is exceptionally easy to do).

-stevieb

The commented out regex grabs everything up to a space greedily... that is, it matches everything up to the last literal space before end of string (so it grabs up to " Vinny"), and $1 is populated with anything not a literal space up to a literal space (or end of string). Put a space in "Vinny" to see for yourself.

The first regex simply captures everything greedily all the way up to the very last non-whitespace character before end of string into $1, and puts the rest in $2. The 'rest' in this case is the last letter in the first name.

-stevieb

thanks I think I got it with your quick explanation.

• Davido's precious regex tester is now online here
• the regex coach program

Grazie Mille for the pointer to the regex coach...I got to playing with it last night and I think it was a good source to test my expressions