use strict;
use warnings;

$_="kkkaaabc"; 
print "String = $_\n";
print "1 $&      Expected: ka     ?? /k?a?/\n" if /k?a?/;
print "2 $&   Expected: kkka   OK\n"    if /k*a?/;
print "3 $&   Expected: kaaa   OK\n"    if /k?a+/;
print "4 $& Expected: kkkaaa OK\n"      if /k+a+/;
print "5 $&      Expected: kaaa   ?? /k?a*/\n" if /k?a*/;
print "6 $& Expected: kkkaaa OK\n"      if /k*a*/;