Regular expression is a pattern that matches input text. The .Net framework provides a regular expression engine that allows for such matching. A pattern consists of one or more characters, operators, and structures. Next, through this article, I will introduce to you the meaning of using regular expressions to match characters in C#.
1. The function of regular expressions: used to describe the characteristics of strings.
2. The meaning of each matching character:
.: means a single character other than \n
[ ] : means that any single character listed in the character array[ ] is arbitrarily taken
| : means "or"
() : means changing priority or "extract group"
* : Restrict the previous expression to appear 0 or more times
+: limits the previous expression to appear once or more times
? : Restrict the previous expression to appear 0 or 1 time
^: means starting with an expression (example: ^http means that the string starts with "http")
$: means ending with an expression (Example: com$ means a string ending with "com")
\d: lowercase \d represents a number between 0-9
\D: uppercase \D means characters other than 0-9
\w : lowercase \w means [a-zA-Z0-9]
\W : uppercase \W means characters other than [a-zA-Z0-9]
\s: lowercase \s means non-visible characters (such as spaces, tabs, \r\n.........)
\S: uppercase \S means characters other than non-visible characters
2. Examples of regular expressions
Match postal code: ^[0-9]{6}$
Match the number between 10 and 25: ^(1[0-9]|2[0-5])$
Approximately match the email format: ^[a-zA-Z0-9_]+@[a-zA-Z0-9]+(\.[a-zA-Z0-9]+){1,2}$
3. Use regular expressions to match strings
citation required:;
() method: to determine whether the given string matches a regular expression
() Method: Extract a string matching the regular expression from the given string
() Method: Extract all strings that match the regular expression from the given string
() Method: Replace all strings that match the regular expression to another string
Summarize
The above is the meaning of using regular expressions to match characters in C# that the editor introduces to you. I hope it will be helpful to you. If you have any questions, please leave me a message and the editor will reply to you in time. Thank you very much for your support for my website!