Solution to disturbing regular expressions with characters such as "S" in the content-php Tutorial

Solution for interfering with regular expressions with characters such as S in the content I found that some characters in the content are displayed in articles, and there is a problem with regular expression matching, such as the following characters:
"S and.

For example, the discuz portal article does not properly handle this issue. I published an article containing the character "S". after the publication, the article is blank. Preliminary speculation is that these special characters conflict with some metacharacters of the regular expression. how can this problem be solved? It seems that it cannot be escaped.

Reply to discussion (solution)

In Escape mode, how can I be added to the pattern modifier?

Escape should be enough. how do you write your code?