---
title: "Alphanumeric regex expression in c#"  
description: "Alphanumeric regex expression in c#"  
author: "Takeshi Okada"  
published: 2013-12-18  
updated: 2013-12-18  
canonical: https://www.mindstick.com/forum/1815/alphanumeric-regex-expression-in-c-sharp  
category: "c#"  
tags: ["c#"]  
reading_time: 1 minute  

---

# Alphanumeric regex expression in c#

I am new in the [programming](https://www.mindstick.com/articles/12214/web-development-company-in-india-laid-on-the-foundation-of-concrete-java-programming) and i [am looking](https://answers.mindstick.com/qa/115463/i-am-looking-for-to-joining-the-mindstick-internship-program-how-to-apply) for a [regular expression](https://www.mindstick.com/articles/11909/java-regex-or-regular-expression-in-java) as

first three [characters](https://answers.mindstick.com/qa/42112/who-is-the-originator-of-avengers-characters) should be alphanumeric followed by a [constant](https://www.mindstick.com/forum/34714/difference-between-statics-vs-constant-in-c-sharp) which is a [special character](https://www.mindstick.com/forum/119/special-character-remove-from-url-or-any-string) and then 1 or more hashes

(3 alphanumeric) (constant) ( one or more hashes)

AB1-# ABC$## etc.

## Replies

### Reply by Anonymous User

Hi Takeshi,\

you can use something like

(\w{3})([^\s])(#+)


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