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Regular Expressions
https://deerchao.net/tutorials/regex/regex.htm
\ b regular expression specified in a special code (Well, some people call it meta-character, metacharacter ), representing the beginning or end of a word, is the word boundary at
. It is another element character matching except newline character arbitrary character
* Is also a meta-character, but it is not representative of the character, not the location, but the number - it specifies * content front can be continuously reused any number of times to get the whole expression match with
\ d is a new metacharacter, matches a single digit (0 or 1 , or 2 , or ......) .
0 \ d {2} - \ d {8}, where \ behind D {2} ({8}) of the front means \ d must match a sequence of repeated 2 times (8 times)
{5,12} is the number of repetitions of not less than 5 times, no more than 12 times
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Metacharacters
| Common metacharacters |
|
| Code |
Explanation |
| . |
It matches any character except newline |
| \w |
Match letters or numbers or an underscore or Chinese characters (? Characters doubtful) |
| \s |
Matches any whitespace |
| \d |
Matching numbers |
| \b |
Matches the beginning or end of a word |
| ^ |
Matches the beginning of the string |
| $ |
The end of the match the string |
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Character escape \
\.with\*. Of course, to find \ itself, you have to use \\
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Character classes, that is, [] range
\ [(0 \ d {2 }?) -]? \ D {8} This expression can match a telephone number in several formats , like (010) 88886666 , or 022-22334455 or 02912345678 like.
The first is an escape character \ (, it can appear 0 or 1 ()? , Followed by a 0, followed by two numbers (\ d {2}), then) or - or space in a, it appears once or absence (?), the last eight digits (\ d {8}).
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Branch condition
With | the different rules separated
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antonym
| Commonly used antisense Code |
|
| Code / Syntax |
Explanation |
| \W |
Not match any letters, numbers, underscores, Chinese characters |
| \S |
Matches any character is not whitespace |
| \D |
Matches any non-numeric characters |
| \B |
Position matching is not the beginning or end of a word |
| [^x] |
In addition to matching x any character other than |
| [^aeiou] |
In addition to matching aeiou any character other than these letters |