Question

Am I putting regex the correct way here to filter out image filename and filetype?

^(\w)+\.(jpg|png|gif)$

the link to the exercise is here:
http://regexone.com/example/4?

The exercise is To capture the name and the extension from a list of files:

task           text                  capture
skip text      .bash_profile        
skip text      workspace.doc        
capture text   img0912.jpg          img0912, jpg    
capture text   updated_img0912.png  updated_img0912, png    
skip text      documentation.html       
capture text   favicon.gif          favicon, gif    
skip text      img0912.jpg.tmp      
skip text      access.lock

Answer 1

You have only one mistake:

You capture only the last character of the filename with (\w)+. This is called “repeat a capturing group“, that is not what you want here. Put the quantifier inside the group to capture the complete name.

    (\w+)

Some notes

1. The starting anchor “^” is not necessarily needed, depends on what you are looking for. For that example it would make no difference.

2. \w works for your example, but will not capture all valid filenames, because it contains only Letters, Digits and the Underscore.