Win8 Strawberry 5.30.3.1 (64)  Tue 01/12/2021 14:15:24
C:\@Work\Perl\monks
>perl -Mstrict -Mwarnings
# pm#11126809

use Regexp::Common qw(number);

my $rx_lat_lon = qr{ (?<! \d) $RE{num}{real} (?! \d) }xms;

for my $lat_lon (
    '123,456',  '12.345, -0',  '  -2. , 0.987',  '  -.0 ,0.987  ',
    '0, -0',  '.0 ,-.0',  '0. , -0.',  ' 0.0 ,  -0.0 ',
    '1, -1',  '.1 ,-.1',  '1. , -1.',  ' 1.2 ,  -1.2 ',
    '123 456',  '123',  'foo',  '123,foo',  'foo,123',  '1.234.5',
    ) {

    my $got_lat_lon =
    my ($lat, $lon) =
    $lat_lon =~ m{ \A \s* ($rx_lat_lon) \s* , \s* ($rx_lat_lon) \s* \z }xms;
  # $lat_lon =~ m{ $rx_lat_lon }xmsg;  # no data validation

    if ($got_lat_lon) {
        printf "%18s -> lat %-10s  lon %-10s \n",
               "'$lat_lon'", n_or_undef($lat), n_or_undef($lon);
        }
    else {
        print "'$lat_lon' FAILED to extract lat/lon \n";
        }

    }

sub n_or_undef { return defined $_[0] ? "'$_[0]'" : 'undef'; }

^Z
         '123,456' -> lat '123'       lon '456'
      '12.345, -0' -> lat '12.345'    lon '-0'
   '  -2. , 0.987' -> lat '-2.'       lon '0.987'
  '  -.0 ,0.987  ' -> lat '-.0'       lon '0.987'
           '0, -0' -> lat '0'         lon '-0'
         '.0 ,-.0' -> lat '.0'        lon '-.0'
        '0. , -0.' -> lat '0.'        lon '-0.'
   ' 0.0 ,  -0.0 ' -> lat '0.0'       lon '-0.0'
           '1, -1' -> lat '1'         lon '-1'
         '.1 ,-.1' -> lat '.1'        lon '-.1'
        '1. , -1.' -> lat '1.'        lon '-1.'
   ' 1.2 ,  -1.2 ' -> lat '1.2'       lon '-1.2'
'123 456' FAILED to extract lat/lon
'123' FAILED to extract lat/lon
'foo' FAILED to extract lat/lon
'123,foo' FAILED to extract lat/lon
'foo,123' FAILED to extract lat/lon
'1.234.5' FAILED to extract lat/lon