use strict;
my $str = 'TAX INVOICE CA MANIN DER SINGH AND ASSOCIATES 253 B 1/12 APSARA ARCADE PUSA ROAD.NEW DELHl-110005 GSTIN No 07APAFD8365H1Z9 Bill to Place of Supply INVOICE No Dated RK Electrical Works RK Electrical Works A-240 Palam Vihar, Delhi GSTIN No:-07BBUPS5612K1Z9 Description of Services Professional Services for Month of July Total Less Discount Taxable Value ADDCGST9% ADDSGST9% Total Amount Chargeable (in words) Rupees One Lac Eighteen Thousand Only Company\'s PAN: AAKFD6723D Note-Please make cheques in favor of "CA Maninder Singh and Associates" A-240 Palam Vihar, Delhi MSA-Tl-02 1-Jul-17 SAC CODE Amount 9982 100000 100000 0 100000 9% 9000 9% 9000 118000.00 For CA Maninder Singh & Associates Authorised Signatory ()-';
my $regex = qr/(GSTIN No:-): (.*?\d\s)/mp;
my $subst = '$1,$2 in $3:';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html