# Column Expression

**URL:** <https://forum.knime.com/t/column-expression/35126>\
**Category:** KNIME Analytics Platform\
**Created:** [August 4, 2021, 11:19pm UTC](https://forum.knime.com/t/column-expression/35126 "2021-08-04T23:19:33Z")\
**Posts on this page:** 1\
**Showing post:** 6

<div class="post-metadata">

**Author:** ![ipazin](https://forum-cdn.knime.com/user_avatar/forum.knime.com/ipazin/32/806_2.png) [@ipazin](https://forum.knime.com/u/ipazin)\
**Post date:** [August 6, 2021, 10:32am UTC](https://forum.knime.com/t/column-expression/35126/6 "2021-08-06T10:32:24Z")

</div>

> [@takbb](#):
>
> I think there might be some cases though where you need to enter a third backslash

Not sure about third but there is definitely a case when you need a fourth one 🙂

> [@Guidance on regexReplace function](https://forum.knime.com/t/guidance-on-regexreplace-function/21734/2):
>
> Hi there @Jeff, to escape backslash character in regex function you need 4 backslashes! So something like this should work: regexReplace($column1$,"c:\\\\MyDir\\\\(Dir1|Dir2|Dir3)\\\\Save\\\\","") More about that [here](https://stackoverflow.com/questions/4025482/cant-escape-the-backslash-with-regex). Also you can use following syntax in [String Manipulation](https://kni.me/n/eOn8ibZnxIkY7XhT) node to obtain file name together with extension: substr($column1$,indexOf($column1$,"\\","b") + 1) Basically it says get me everything after last backslash. Hope this helps! Br, Ivan

Br,  
Ivan

---

_[View the full topic](https://forum.knime.com/t/column-expression/35126)._