This seems to pass my limited testing...
my $string = '1,2,a,b,3';
$string =~ s/( (?:(?<!\d)(?:,|\.)(?!\s*\d)) |
print $string, "\n";
It's really ugly, but triggers a substitution all of the following cases:
- Comma or dot is not surrounded by digits, with optional whitespace after the comma or dot.
- Comma or dot doesn't have a digit to the left, with optional whitespace after the comma or dot.
- Comma or dot doesn't have a digit to the right, with optional whitespace after the comma or dot.
So I think it meets your spec. If this is homework I would seriously recommend immersing yourself in the POD's so that you'll be able to explain to your professor how it is you came up with such a wild RE. For that matter, it's time that I re-read the POD's, as I'm not convinced that it really needs to be so explicit to work properly.
See perlre to learn about zero-width lookahead and lookbehind (positive and negative). Also read perlretut and perlop under the "Regexp quote like characters" section, for starters.
Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
Read Where should I post X? if you're not absolutely sure you're posting in the right place.
Please read these before you post! —
Posts may use any of the Perl Monks Approved HTML tags:
Outside of code tags, you may need to use entities for some characters:
- a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
Link using PerlMonks shortcuts! What shortcuts can I use for linking?
See Writeup Formatting Tips and other pages linked from there for more info.
| & || & |
| < || < |
| > || > |
| [ || [ |
| ] || ] ||