正则表达式是什么？

Question

The variable $description which contains some text may also contain a string like so:

!some_text_that_may_be_different_each_time!

I need to get rid of these, so I tried:

$new_description = preg_replace("!.+?!", '', $description);

But no luck. What would be a good way to get rid of these strings?

Also removing them may leave extra spaces. For example:

Hi world how are ya !asdasdasdasdasd! blue chickens

would become

Hi world how are ya  blue chickens

As you can see now there are 2 spaces between ya and blue . I would like these to turn to one space as well.

Answer 1

Try a regex like

/![^!]+! */

note the " *" at the end to eat up any spaces after it.

Edit : Additionally, you didn't use the / / delimiters denoting the regex in your example, which is probably why your test didn't work. I opted for [^!]+ (string not containing '!') instead of .+?, which is an ungreedy match, out of habit. I'm not certain if it's faster or not, but in this example it probably doesn't matter.

Answer 2

Try this:

$new_description = preg_replace("/\s*![^!]+!/", '', $description);

If there is a space(s) before the ! you will replace it, and therefore you will just have one space (the last one).
Notice that what you were doing is use "!" as the delimiters of the regex and therefore it wasn't matching.

Answer 3

There is actually a simple method. Just replace everthing in between exclamation points and then replace two spaces with one space.

$new_description = preg_replace("!.*?!", '', $description);
$new_description = preg_replace(" +", ' ', $new_description);