


What is a regular expression? His usage? What are his characteristics? (with detailed explanation)
The previous article introduced you to "Reading file related operations after finishing the file operation in one day (with detailed explanation)". This article continues to introduce to you what is a regular expression? His usage? What are his characteristics? (With detailed explanation), let’s give it together and learn! ! !
#1: A brief introduction to regular expressions:
Regular expressions describe the string arrangement pattern A custom syntax rule
Don't use regular expressions if the task can be accomplished using string processing functions
There are some Complex operations can only be completed with regular expressions
Regular expression is also called a pattern expression
Regular expression The formula is to compare, split, match, search, and replace the input string information by constructing a pattern with specific rules.
2. What is Regular expression
Example:
*/<img \s+src=\" . *?\" V/ alt="What is a regular expression? His usage? What are his characteristics? (with detailed explanation)" >/" 它就是正则表达式
A bunch of messy characters piled together, mysterious symbols, with strange meanings.
3. Learn what regular expressions can do
#Verify whether the username length is legal.
Verify email rules
Verify mobile phone number
Verify URL
BBS Editor
- ##QQ Chat Expression ##News Collector, (Thief Program)
- Regular expression is also a string
- A string composed of characters with special meaning
- has certain writing rules and is also a pattern
- is regarded as A derogatory term for the language, because it uses some special characters to write a string according to the rules to form a pattern-regular expression
- If the regular expression does not match the function When used together, it is just an ordinary string. Only if the regular expression is amplified and used in a function can the role of the regular expression be brought into play
- posix extended regular expression ereg
- perl compatible regular expression preg
- It is recommended to use per1 compatible regular expression function library
- How to write regular expression patterns
- Learn the powerful processing functions of regular expressions
- Regular delimiters
- In regular expressions Atoms
- Metacharacters (atom modifiers) of regular expressions
- Pattern modifiers of regular expressions
- Recommended learning: "
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