In asking this question, I actually did first review this post from some months ago. But I want to take my question one step further and ask when should old programming books be thrown out? Specifically, our office has several copies of books that were written specifically to older versions of languages such as PHP4, ActionScript 1 etc.
My initial impression is to simply toss these books and purchase more generic entry level books for teaching those who need to learn a specific language and to then purchase the classics that will help our entire staff develop better code such as Patterns of Enterprise Application Architecture, Code Complete, etc. But is there any benefit to hanging onto copies of books that were for a version of a language that is now either dead or outdated?
UPDATE: Thank you to those who suggested donating the books to the local library. I think that's just what we'll do!