Regular expression for a double word

Question

I am trying to write a regular expression that will detect a word that is repeated twice, e.g., greatgreat or appleapple. I could not find any way to do this, after hours of trying I am posting it here to see if anyone can help.

Answer 1

Try this (example on RegExr):

(\w+)\1

If you want to make sure that the whole sting is a doubled word add anchors:

^(\w+)\1$

For more information see the docs - "Round brackets for grouping and backreferences".