Beefy Boxes and Bandwidth Generously Provided by pair Networks
Syntactic Confectionery Delight
 
PerlMonks  

How do I add commas to a number?

( #2145=categorized question: print w/ replies, xml ) Need Help??
Contributed by vroom on Jan 18, 2000 at 22:54 UTC
Q&A  > numbers


Answer: How do I add commas to a number?
contributed by Fastolfe

See perlfaq5: How can I output my numbers with commas added?. In addition, that FAQ apparently used to include the following, contributed by Andrew Johnson, as well:

sub commify { my $input = shift; $input = reverse $input; $input =~ s/(\d\d\d)(?=\d)(?!\d*\.)/$1,/g; return reverse $input; }
Answer: How do I add commas to a number?
contributed by Roy Johnson

A lookaround method that will work on any numbers embedded in a string (but will not commify after a decimal point):

sub commify { local $_ = shift; s{(?<!\d|\.)(\d{4,})} {my $n = $1; $n=~s/(?<=.)(?=(?:.{3})+$)/,/g; $n; }eg; return $_; }
If you prefer the FAQ rule of only working on things that begin with digits or -,
sub commify { local $_ = shift; s{(?:(?<=^)|(?<=^-))(\d{4,})} {my $n = $1; $n=~s/(?<=.)(?=(?:.{3})+$)/,/g; $n; }e; return $_; }
This one does a single pattern match and then uses substr() to insert the commas:
sub commify { local $_ = shift; if (/^-?(\d{4,})/g) { for (my $p=$+[1]; $p>$-[1]; $p-=3) { substr($_,$p,0) = ',' } } return $_; }
Answer: How do I add commas to a number?
contributed by Dodger

I know it's eons old but I just noticed this (when looking for if there was some easy one-liner for this); it's good that that was removed from that FAQ mentioned above in the first answer.

Since return() casts in list context:

return reverse $input;

will not work (at least not as expected), as it reverses the list of the result, e.g. ('098,765,432,1') to ('098,765,432,1') (it's a list of one).

What you'd need is:

return scalar reverse $input;

Please (register and) log in if you wish to add an answer



  • 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:
    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
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others pondering the Monastery: (5)
    As of 2015-07-06 00:45 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









      Results (68 votes), past polls