$ perl -de1

Loading DB routines from perl5db.pl version 1.53
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(-e:1):	1
  DB<1> $str =  '\\x{A3f4}'                                                     

  DB<2> p $str                                                                  
\x{A3f4}
                                                                   



##</code><code>##

  DB<2> print $str                                                              
\x{A3f4}
  DB<3> print "$str"                                                            
\x{A3f4}

##</code><code>##

  DB<3> if ( $str =~ /(\\x{[A-F\d]+})/i ) { print $1 }                          
Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by <-- HERE in m/(\\x{ <-- HERE [A-F\d]+})/ at (eval 13)[/usr/share/perl/5.28/perl5db.pl:738] line 2.
   

##</code><code>##

at (eval 13)[/usr/share/perl/5.28/perl5db.pl:738] line 2.
	eval 'no strict; ($@, $!, $^E, $,, $/, $\\, $^W) = @DB::saved;package main; $^D = $^D | $DB::db_stop;
if ( $str =~ /(\\\\x{[A-F\\d]+})/i ) { print $1 };
' called at /usr/share/perl/5.28/perl5db.pl line 738
	DB::eval called at /usr/share/perl/5.28/perl5db.pl line 3138
	DB::DB called at -e line 1
Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by <-- HERE in m/(\\x{ <-- HERE [A-F\d]+})/ at (eval 13)[/usr/share/perl/5.28/perl5db.pl:738] line 2.
 at (eval 13)[/usr/share/perl/5.28/perl5db.pl:738] line 2.
	eval 'no strict; ($@, $!, $^E, $,, $/, $\\, $^W) = @DB::saved;package main; $^D = $^D | $DB::db_stop;
if ( $str =~ /(\\\\x{[A-F\\d]+})/i ) { print $1 };
' called at /usr/share/perl/5.28/perl5db.pl line 738
	DB::eval called at /usr/share/perl/5.28/perl5db.pl line 3138
	DB::DB called at -e line 1
Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by <-- HERE in m/(\\x{ <-- HERE [A-F\d]+})/ at (eval 13)[/usr/share/perl/5.28/perl5db.pl:738] line 2.
 at (eval 13)[/usr/share/perl/5.28/perl5db.pl:738] line 2.
	eval 'no strict; ($@, $!, $^E, $,, $/, $\\, $^W) = @DB::saved;package main; $^D = $^D | $DB::db_stop;
if ( $str =~ /(\\\\x{[A-F\\d]+})/i ) { print $1 };
' called at /usr/share/perl/5.28/perl5db.pl line 738
	DB::eval called at /usr/share/perl/5.28/perl5db.pl line 3138
	DB::DB called at -e line 1
\x{A3f4}


##</code><code>##

eval 'no strict; ($@, $!, $^E, $,, $/, $\\, $^W) = @DB::saved;package main; $^D = $^D | $DB::db_stop;
if ( $str =~ /(\\\\x{[A-F\\d]+})/i ) { print $1 };


##</code><code>##

  DB<5> $str =  '123X12'                                                        

  DB<6> p $str                                                                  
123X12
  DB<7> if ( $str =~ /^(\d{2,4})[^\d](\d{2})/) { print "$1;$2" }                
123;12
  DB<8> $str =  '123{12'                                                        

  DB<9> if ( $str =~ /^(\d{2,4})[^\d](\d{2})/) { print "$1;$2" }                
123;12