preg_replace and asterisk

Question

I want to replace non-word non-space characters with spaces. There can be many symbol characters consecutively, so I'm using the regex below

[^\s\w]*

So, the code I'm using is:

$str = 'email@domain.com';
echo preg_replace('/[^\s\w]*/', ' ', $str);

I was expecting to get email domain com but I get e m a i l d o m a i n c o m, whitespaces between each character. If I remove the asterisk like following

echo preg_replace('/[^\s\w]/', ' ', $str);

then I get the desired email domain com. But if input is email@@domain.com then this regex will give email domain com with two whitespaces between email and domain, which is not what I want.

Can anyone explain why [^\s\w]* doesn't work, and how can I achieve what I want?

Replace `*` with `+` - `/[^\s\w]+/`, `'/[^\s\w]*/'` matches empty spaces before each non matching char. — Wiktor Stribiżew, Jun 12 '17 at 15:44
The `preg_replace('/[^\s\w]+/', ' ', $str)` is exactly what you need. — Wiktor Stribiżew, Jun 13 '17 at 09:17
@WiktorStribiżew stupid me. I later realised that you were absolutely right — NecipAllef, Jun 13 '17 at 09:18

score 1 · Accepted Answer · answered Jun 12 '17 at 15:50

1

This is happening because the asterisk matches 0 or more instances of [^\s\w]. So it's matching 0 instances, and then replacing it with a space. Use plus (+) if you want to make sure there's at least one match: /[^\s\w]+/.

answered Jun 12 '17 at 15:50

sorayadragon

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preg_replace and asterisk

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