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Including Files with include()

The include() statement enables you to incorporate files into your PHP documents. PHP code in these files can be executed as if it were part of the main document. This can be useful for including library code in multiple pages.

Having created a really useful function, your only option until now would have been to paste it into every document that needs to use it. Of course, if you discover a bug or want to add a feature, you would have to find every page that uses the function to make the change. The include() statement can save you from this chore. You can add the function to a single document and, at runtime, read it into any page that needs it. The include() statement requires a single argument: a relative path ...