正则表达式以不同方式

Im testing on this website: Regex Tester

And I came up with this expression /[\w ]/ that does exactly what I want on that website, which is to select special characters.

BUT when I use it in my PHP file it isnt working.

In my PHP i have this function:

function removeSpecialChar($str) {
    return str_replace("/[^\w ]/", "", $str);
}

For example lets say that $str="asdf1234 !"#¤asd"

It should return "asdf1234 asd" but it isnt, any ideas?

Use preg_replace when you need the regex-based replacement. str_replace will treat the given string as is - without any special meaning given to metacharacters.

$str = 'asdf1234 !\"#¤asd';

function removeSpecialChar($str) {
    return preg_replace('/[^\w ]/', '', $str);
}

echo removeSpecialChar($str); // asdf1234 asd