How to use regex modifiers when searching in a text editor?

Question

Regular Expressions

For example, in code I often use a construction like #regular_exp#siU. In sublime text, when searching through a document, this syntax does not work. Earlier somewhere I met the use of modifiers in the form of a prefix. I can't find the syntax right now. Tell?

Answer 1

Just add to the beginning of the regular expression
(?si)