Python Regex to detect underscore between letters

Question

How do I make a regex in python that returns a string with all underscores between lowercase letters? For example, it should detect and return: 'aa_bb_cc' , 'swd_qq' , 'hello_there_friend'

But it should not return these: 'aA_bb' , 'aa_' , '_ddQ' , 'aa_baa_2cs'

My code is ([a-z]+_[a-z]+)+ , but it returns only one underscore. It should return all underscores seperated by lowercase letters.

For example, when I pass the string "aab_cbbbc_vv", it returns only 'aab_cbbbc' instead of 'aab_cbbbc_vv'

Thank you

Answer 1

Your regex is almost correct. If you change it to:

^([a-z]+)(_[a-z]+)+$

It woks as you can check here.

^ - matches the beginning of the string

$ - the end of the string

You need these so that you are not getting partial matches when matching the strings you don't want to get matched.