Books Turned Into Movies!

I have read both books 'The Host By Stephenie Meyer' & 'The Mortal Instruments Series By Cassandra Clare'. I am very excited for the movies to come out. Has we all know books to movies can be very accurate like the 'Harry Potter Series' or not as accurate like the 'Twilight Series'. Although I highly doubt this would happen with these books, I an super excited for the movies. My fandoms are coming to life.