use strict;

my @strings = qw (ThisString SomeOtherString);

foreach (@strings) {
  s/([a-z])([A-Z])/"$1:$2"/eg;`
  my @tokens = split /:/;
  print join "\n", @tokens;
  print "\n";
}

__END__

# Output: 

This
String
Some 
Other 
String