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This article mainly introduces "the usage of C# regular expression Regex class". In daily operation, I believe that many people have doubts about the usage of C# regular expression Regex class. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts about "the usage of C# regular expression Regex class". Next, please follow the editor to study!

The Regex class represents an immutable (read-only) regular expression. It also contains a variety of static methods that allow you to use other regular expression classes without explicitly creating instances of other classes.

Overview of the basics of regular expressions

What is a regular expression

When writing string handlers, there is often a need to find strings that conform to some complex rules. Regular expressions are the tools used to describe these rules. In other words, a regular expression is the code that records text rules.

Typically, when we use WINDOWS to find files, we use wildcards (* and?). If you want to find all the Word documents in a directory, you can use * .doc to find it, where * is interpreted as any string. Like wildcards, regular expressions are a tool for text matching, except that they describe your requirements more accurately than wildcards-at the expense of being more complex.

I. C # regular expression symbol pattern

Character character

Description

\

Escape character, escape a character with a special function into a normal character, or vice versa

^

Match the starting position of the input string

$

Matches the end position of the input string

*

Matches the previous zero or more subexpressions

+

Matches the previous one or more subexpressions

?

Matches the previous zero or once subexpression

{n}

N is a non-negative integer that matches the previous n-th subexpression.

{n,}

N is a non-negative integer that matches at least the previous n-th subexpression.

{n,m}

M and n are non-negative integers, where n

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