in reply to Insert into string

Someone has to say it. You appear to be editing XML, and therefore you'd be better off, in the long run, using an XML module to Do It Properly.

($_='kkvvttuu bbooppuuiiffss qqffssmm iibbddllffss')
=~y~b-v~a-z~s; print

In Section Seekers of Perl Wisdom