PHP Regular expression - Remove all non-alphanumeric characters

Question

I use PHP.

My string can look like this

This is a string-test width åäö and some über+strange characters: _like this?

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Answer 1

Are you perhaps looking for \W?

Something like:

/[\W_]*/

Matches all non-alphanumeric character and underscores.

\w matches all word character (alphabet, numeric, underscores)

\W matches anything not in \w.

So, \W matches any non-alphanumeric characters and you add the underscore since \W doesn't match underscores.

EDIT: This make your line of code become:

preg_replace("/[\W_]*/", ' ', $string);

The ' ' means that all matching characters (those not letter and not number) will become white spaces.

reEDIT: You might additionally want to use another preg_replace to remove all the consecutive spaces and replace them with a single space, otherwise you'll end up with:

This is a string test width     and some  ber strange characters   like this 

You can use:

preg_replace("/\s+/", ' ', $string);

And lastly trim the beginning and end spaces if any.