c# - Regular expression to get last 3 characters of a string

Question

I want to write a regular expression which will take only last 3 char of a string and append some constant string to it.

I am using C#. I am trying to make regular expression as database entry. Later Read this entry in application and do the transformation based on regex in C#.

Something like :

stringVal.Trim().Substring(0, stringVal.Trim().Length - 3) + ".ConstantValue"

Answer 1

Use this regular expression :

.{3}$

If you want to avoid spaces at end and can use capturing groups (you didn't precise the language or regex flavour), use

(.{3})s*$

But note that there's no obvious reason to use a regex here instead of slicing the string.