Combine multiple regex expressions into a single line

January 5, 2022

I am trying to get the following Regex expressions into a single line.

filename = Regex.Replace(filename, @"[^a-z0-9\s-!/\-_\.\*\(\)']", ""); // Remove all non valid chars          
    filename = Regex.Replace(filename, @"\s+", " ").Trim(); // convert multiple spaces into one space  
    filename = Regex.Replace(filename, @"\s", "_"); // //Replace spaces by dashes

>Solution :

You can use

filename = Regex.Replace(filename, @"[^a-z0-9\s!/_.*()'-]|^\s+|\s+$|(\s+)", m => m.Groups[1].Success ? "_" : "");

The regex matches

[^a-z0-9\s!/_.*()'-]| – any char but lowercase ASCII letters, digits, whitespace, !, /, _, ., *, (, ), ' and -, or
^\s+| – start of string and then one or more whitespaces, or
\s+$| – one or more whitespaces and then end of string
(\s+) – Group 1: one or more whitespaces in any other context.