Question

I am not familiar with regular expression.

For a string, I want to replace all the non-letter and non-digit characters with space, and then merge the spaces so that there is no two consecutive spaces.

How to achieve that using regular expression?

Answer 1

Use two replacements:

1. Replace [^a-zA-Z0-9] by a space
2. Replace [ ]{2,} by a single space (the character class is only needed here because SO’s parser messes up – usually a space suffices on its own)

In PowerShell that’d look like

$s -replace '[^a-zA-Z0-9]', ' ' -replace ' {2,}', ' '