PHP字符串替换修饰符

Question

I am trying to write some string replace functions, and rather than ask how to do a specific replace, I want to know more about modifiers so I can do it myself

Take this for example:

preg_replace('~[\W\s]~', ' ', $input);

or

strlen(preg_replace('![^A-Z]+!', '', $s));

What are those called? (~[\\W\\s]~) (![^AZ]+!) They make very little sense to read or make up a new one. Where can I find all of them? Or learn how to write them?

Answer 1

They are called Regular Expressions. From http://www.regular-expressions.info , 'A regular expression (regex or regexp for short) is a special text string for describing a search pattern. You can think of regular expressions as wildcards on steroids.'

Here is a site with references and a playground to test working with them.

http://regexr.com