Getting started with RegEx

Introduction

Regular expressions are a logical formula for the manipulation of strings and special characters.
A "regular string" is composed of a specific combination of characters defined in advance.
This "rule string" describes the string to match when searching for text. It is used to express a filtering logic for a string, usually used to retrieve and replace text that conforms to a pattern (rule).
Regular expressions in mainstream operating systems (Linux, Unix, Windows, etc.), mainstream development languages (PHP, C#, C++, Java, Javascript, VB, Python, etc.) and tens of thousands of applications Figure.

Rule

Basic character

Base symbol

Combine characters to form a regular expression and take the search in the text 'HELLO, friend, my name is Bynav.' as an example. (& refers to regular expressions)