正则表达式删除除字母数字和空格之外的任何内容（在PHP中）

Question

I'm trying to remove, via regular expression, all but alphanumeric characters & spaces.

Here's the conversion I am hoping to achieve.

"I am a string" → "I am a string"
"How are you?" → "How are you"
"#53-Jeff" → "53-Jeff"

So far I have this:

return preg_replace("/[^0-9a-zA-Z]/","", $val);

But being a regex novice, I can't figure out how to insert a space. I had odd results when I tried.

Answer 1

Inserting a space is just as simple as you expect it to be:

preg_replace("/[^0-9a-zA-Z ]/", "", $val);

Btw. your third example is not clear to me: Do you want to replace the - too? If not, you need to add it to the character list too.

See this for a running example.

Answer 2

This should work:

preg_replace("/[^0-9a-zA-Z -]/", "", $val);

Keep in mind to add the "-" to the very end of the character set block, or it might get interpreted as a range operator.

Depending on your regex flags (if whitespace/comments are enabled) you might need to replace the " " (right before the "-" ) with a "\\s" or (stricter) "\\ " .