Is it possible to repeat a captured group in the substitution in regular expressions?

Question

Is it possible with regex to repeat a captured group an amount of times with the added restriction that the amount to repeat is also found in a capture group?

Example:

Regex: /(a)([0-9])/g
String: ba1na3na2
Expected result: banaaanaa

I have never seen anything that does this, but maybe I have been looking in the wrong places. Note: I am using Perl - but I am interested to see answers for other flavours as well.

Answer 1

In perl this regular expression will give you the expected result, your regexp is a match, while the s regular expression is a substitution:

s/(a)([0-9])/$1 x $2/eg;

Like this:

my $str = 'ba1na3na2';
$str =~ s/(a)([0-9])/$1 x $2/eg;
print $str;

banaaanaa

• The e modifier evaluates the right-hand side as an expression.
• The x operator repeates the string.

Update:

As @AvinashRaj says it might be s/(a)([0-9]+)/$1 x $2/eg; is more approriate. Depending on if you want ba20nana to become

• baa0nana

or

• baaaaaaaaaaaaaaaaaaaanana