Use the /e switch (see the end of the Modifiers section in perlre):

use strict;
use warnings;

my $str = "1 2 345 23";

$str =~ s/(\d+)/add($1)/ge;

print $str;

sub add {
    my ($num) = @_;
    return $num + 10;
}
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Prints:

11 12 355 33
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Note that your sample was missing 's' in front of the first / that denotes substitution instead of match and was missing capture parenthesis in the match. Also, you don't need & to call a function, and in fact should (almost) never use that call syntax.

Oh, and a sub called 'add' should add, not multiply. If you can't get simple names like that right you are going to cause a lot of grief for someone down the road!

Also, you don't need & to call a function, and in fact should (almost) never use that call syntax.

To expand this bit, &function was the perl4 way to invoke subroutines. In perl5, &function

• passes the current @_ to the invoked subroutine
• overrides function prototypes

Function prototypes? You should (almost) never use that... see perlsub.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

kepler: Please see also Variables related to regular expressions in perlvar for more info on  $1 $2 $3 ... and many other fine regex variables.

---

Give a man a fish:  <%-{-{-{-<

How can I do this? $str =~ s/\d+/&add($1)/gi; doesn't work

s/gi/ge - since i is case insensitive, e is eval ;-) And! capture to get $1:

$str =~ s/(\d+)/&add($1)/ge;
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...and &add() is soo perl4...

#!/usr/bin/perl -l

# http://perlmonks.org/?node_id=1172179

use strict;
use warnings;

sub add
  {
  4 * shift;
  }

$_ = '123 - 4 - 75 - 12';
print;

s/(\d+)/ add($1) /ge;

print;
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